_docs_ja.utf8.txt

@advanced_1000_h1
#Advanced

@advanced_1001_a
# Result Sets

@advanced_1002_a
# Large Objects

@advanced_1003_a
# Linked Tables

@advanced_1004_a
# Transaction Isolation

@advanced_1005_a
# Multi-Version Concurrency Control (MVCC)

@advanced_1006_a
# Clustering / High Availability

@advanced_1007_a
# Two Phase Commit

@advanced_1008_a
# Compatibility

@advanced_1009_a
# Standards Compliance

@advanced_1010_a
# Run as Windows Service

@advanced_1011_a
# ODBC Driver

@advanced_1012_a
# Using H2 in Microsoft .NET

@advanced_1013_a
# ACID

@advanced_1014_a
# Durability Problems

@advanced_1015_a
# Using the Recover Tool

@advanced_1016_a
# File Locking Protocols

@advanced_1017_a
# File Locking Method 'Serialized'

@advanced_1018_a
# Protection against SQL Injection

@advanced_1019_a
# Protection against Remote Access

@advanced_1020_a
# Restricting Class Loading and Usage

@advanced_1021_a
# Security Protocols

@advanced_1022_a
# SSL/TLS Connections

@advanced_1023_a
# Universally Unique Identifiers (UUID)

@advanced_1024_a
# Settings Read from System Properties

@advanced_1025_a
# Setting the Server Bind Address

@advanced_1026_a
# Pluggable File System

@advanced_1027_a
# Limits and Limitations

@advanced_1028_a
# Glossary and Links

@advanced_1029_h2
Result Sets

@advanced_1030_h3
#Statements that Return a Result Set

@advanced_1031_p
# The following statements return a result set: <code>SELECT, EXPLAIN, CALL, SCRIPT, SHOW, HELP</code>. All other statements return an update count. 

@advanced_1032_h3
行数の制限

@advanced_1033_p
# Before the result is returned to the application, all rows are read by the database. Server side cursors are not supported currently. If only the first few rows are interesting for the application, then the result set size should be limited to improve the performance. This can be done using <code>LIMIT</code> in a query (example: <code>SELECT * FROM TEST LIMIT 100</code>), or by using <code>Statement.setMaxRows(max)</code>. 

@advanced_1034_h3
大きなResult Set と外部ソート

@advanced_1035_p
# For large result set, the result is buffered to disk. The threshold can be defined using the statement <code>SET MAX_MEMORY_ROWS</code>. If <code>ORDER BY</code> is used, the sorting is done using an external sort algorithm. In this case, each block of rows is sorted using quick sort, then written to disk; when reading the data, the blocks are merged together. 

@advanced_1036_h2
大きなオブジェクト

@advanced_1037_h3
大きなオブジェクトのソートと読み込み

@advanced_1038_p
# If it is possible that the objects don't fit into memory, then the data type CLOB (for textual data) or BLOB (for binary data) should be used. For these data types, the objects are not fully read into memory, by using streams. To store a BLOB, use <code>PreparedStatement.setBinaryStream</code>. To store a CLOB, use <code>PreparedStatement.setCharacterStream</code>. To read a BLOB, use <code>ResultSet.getBinaryStream</code>, and to read a CLOB, use <code>ResultSet.getCharacterStream</code>. When using the client/server mode, large BLOB and CLOB data is stored in a temporary file on the client side. 

@advanced_1039_h3
#When to use CLOB/BLOB

@advanced_1040_p
# This database stores large LOB (CLOB and BLOB) objects as separate files. Small LOB objects are stored in-place, the threshold can be set using <a href="grammar.html#set_max_length_inplace_lob" class="notranslate" >MAX_LENGTH_INPLACE_LOB</a>, but there is still an overhead to use CLOB/BLOB. Because of this, BLOB and CLOB should never be used for columns with a maximum size below about 200 bytes. The best threshold depends on the use case; reading in-place objects is faster than reading from separate files, but slows down the performance of operations that don't involve this column. 

@advanced_1041_h3
#Large Object Compression

@advanced_1042_p
# CLOB and BLOB values can be compressed by using <a href="grammar.html#set_compress_lob" class="notranslate" >SET COMPRESS_LOB</a>. The LZF algorithm is faster but needs more disk space. By default compression is disabled, which usually speeds up write operations. If you store many large compressible values such as XML, HTML, text, and uncompressed binary files, then compressing can save a lot of disk space (sometimes more than 50%), and read operations may even be faster. 

@advanced_1043_h2
リンクテーブル

@advanced_1044_p
# This database supports linked tables, which means tables that don't exist in the current database but are just links to another database. To create such a link, use the <code>CREATE LINKED TABLE</code> statement: 

@advanced_1045_p
# You can then access the table in the usual way. Whenever the linked table is accessed, the database issues specific queries over JDBC. Using the example above, if you issue the query <code>SELECT * FROM LINK WHERE ID=1</code>, then the following query is run against the PostgreSQL database: <code>SELECT * FROM TEST WHERE ID=?</code>. The same happens for insert and update statements. Only simple statements are executed against the target database, that means no joins. Prepared statements are used where possible. 

@advanced_1046_p
# To view the statements that are executed against the target table, set the trace level to 3. 

@advanced_1047_p
# If multiple linked tables point to the same database (using the same database URL), the connection is shared. To disable this, set the system property <code>h2.shareLinkedConnections=false</code>. 

@advanced_1048_p
# The statement <a href="grammar.html#create_linked_table" class="notranslate" >CREATE LINKED TABLE</a> supports an optional schema name parameter. 

@advanced_1049_h2
トランザクション分離

@advanced_1050_p
# Transaction isolation is provided for all data manipulation language (DML) statements. Most data definition language (DDL) statements commit the current transaction. See the <a href="grammar.html">Grammar</a> for details. 

@advanced_1051_p
# This database supports the following transaction isolation levels: 

@advanced_1052_b
Read Committed (コミット済み読み取り)

@advanced_1053_li
# This is the default level. Read locks are released immediately. Higher concurrency is possible when using this level.

@advanced_1054_li
# To enable, execute the SQL statement <code>SET LOCK_MODE 3</code>

@advanced_1055_li
# or append <code>;LOCK_MODE=3</code> to the database URL: <code>jdbc:h2:~/test;LOCK_MODE=3</code> 

@advanced_1056_b
Serializable (直列化)

@advanced_1057_li
# To enable, execute the SQL statement <code>SET LOCK_MODE 1</code>

@advanced_1058_li
# or append <code>;LOCK_MODE=1</code> to the database URL: <code>jdbc:h2:~/test;LOCK_MODE=1</code> 

@advanced_1059_b
Read Uncommitted (非コミット読み取り)

@advanced_1060_li
# This level means that transaction isolation is disabled.

@advanced_1061_li
# To enable, execute the SQL statement <code>SET LOCK_MODE 0</code>

@advanced_1062_li
# or append <code>;LOCK_MODE=0</code> to the database URL: <code>jdbc:h2:~/test;LOCK_MODE=0</code> 

@advanced_1063_p
# When using the isolation level 'serializable', dirty reads, non-repeatable reads, and phantom reads are prohibited. 

@advanced_1064_b
Dirty Reads (ダーティリード)

@advanced_1065_li
# Means a connection can read uncommitted changes made by another connection.

@advanced_1066_li
# Possible with: read uncommitted 

@advanced_1067_b
Non-Repeatable Reads (反復不可能読み取り)

@advanced_1068_li
# A connection reads a row, another connection changes a row and commits, and the first connection re-reads the same row and gets the new result.

@advanced_1069_li
# Possible with: read uncommitted, read committed 

@advanced_1070_b
Phantom Reads (ファントムリード)

@advanced_1071_li
# A connection reads a set of rows using a condition, another connection inserts a row that falls in this condition and commits, then the first connection re-reads using the same condition and gets the new row.

@advanced_1072_li
# Possible with: read uncommitted, read committed 

@advanced_1073_h3
テーブルレベルロック

@advanced_1074_p
# The database allows multiple concurrent connections to the same database. To make sure all connections only see consistent data, table level locking is used by default. This mechanism does not allow high concurrency, but is very fast. Shared locks and exclusive locks are supported. Before reading from a table, the database tries to add a shared lock to the table (this is only possible if there is no exclusive lock on the object by another connection). If the shared lock is added successfully, the table can be read. It is allowed that other connections also have a shared lock on the same object. If a connection wants to write to a table (update or delete a row), an exclusive lock is required. To get the exclusive lock, other connection must not have any locks on the object. After the connection commits, all locks are released. This database keeps all locks in memory. 

@advanced_1075_h3
ロックタイムアウト

@advanced_1076_p
# If a connection cannot get a lock on an object, the connection waits for some amount of time (the lock timeout). During this time, hopefully the connection holding the lock commits and it is then possible to get the lock. If this is not possible because the other connection does not release the lock for some time, the unsuccessful connection will get a lock timeout exception. The lock timeout can be set individually for each connection. 

@advanced_1077_h2
#Multi-Version Concurrency Control (MVCC)

@advanced_1078_p
# The MVCC feature allows higher concurrency than using (table level or row level) locks. When using MVCC in this database, delete, insert and update operations will only issue a shared lock on the table. An exclusive lock is still used when adding or removing columns, when dropping the table, and when using <code>SELECT ... FOR UPDATE</code>. Connections only 'see' committed data, and own changes. That means, if connection A updates a row but doesn't commit this change yet, connection B will see the old value. Only when the change is committed, the new value is visible by other connections (read committed). If multiple connections concurrently try to update the same row, the database waits until it can apply the change, but at most until the lock timeout expires. 

@advanced_1079_p
# To use the MVCC feature, append <code>;MVCC=TRUE</code> to the database URL: 

@advanced_1080_p
# MVCC is disabled by default. The MVCC feature is not fully tested yet. The limitations of the MVCC mode are: it can not be used at the same time as <code>MULTI_THREADED=TRUE</code>; the complete undo log must fit in memory when using multi-version concurrency (the setting <code>MAX_MEMORY_UNDO</code> has no effect). It is not possible to enable or disable this setting while the database is already open. The setting must be specified in the first connection (the one that opens the database). 

@advanced_1081_h2
クラスタリング / 高可用性

@advanced_1082_p
# This database supports a simple clustering / high availability mechanism. The architecture is: two database servers run on two different computers, and on both computers is a copy of the same database. If both servers run, each database operation is executed on both computers. If one server fails (power, hardware or network failure), the other server can still continue to work. From this point on, the operations will be executed only on one server until the other server is back up. 

@advanced_1083_p
# Clustering can only be used in the server mode (the embedded mode does not support clustering). The cluster can be re-created using the <code>CreateCluster</code> tool without stopping the remaining server. Applications that are still connected are automatically disconnected, however when appending <code>;AUTO_RECONNECT=TRUE</code>, they will recover from that. 

@advanced_1084_p
# To initialize the cluster, use the following steps: 

@advanced_1085_li
#Create a database 

@advanced_1086_li
#Use the <code>CreateCluster</code> tool to copy the database to another location and initialize the clustering. Afterwards, you have two databases containing the same data. 

@advanced_1087_li
#Start two servers (one for each copy of the database) 

@advanced_1088_li
#You are now ready to connect to the databases with the client application(s) 

@advanced_1089_h3
CreateClusterツールを使用する

@advanced_1090_p
# To understand how clustering works, please try out the following example. In this example, the two databases reside on the same computer, but usually, the databases will be on different servers. 

@advanced_1091_li
#Create two directories: <code>server1, server2</code>. Each directory will simulate a directory on a computer. 

@advanced_1092_li
#Start a TCP server pointing to the first directory. You can do this using the command line: 

@advanced_1093_li
#Start a second TCP server pointing to the second directory. This will simulate a server running on a second (redundant) computer. You can do this using the command line: 

@advanced_1094_li
#Use the <code>CreateCluster</code> tool to initialize clustering. This will automatically create a new, empty database if it does not exist. Run the tool on the command line: 

@advanced_1095_li
#You can now connect to the databases using an application or the H2 Console using the JDBC URL <code>jdbc:h2:tcp://localhost:9101,localhost:9102/~/test</code> 

@advanced_1096_li
#If you stop a server (by killing the process), you will notice that the other machine continues to work, and therefore the database is still accessible. 

@advanced_1097_li
#To restore the cluster, you first need to delete the database that failed, then restart the server that was stopped, and re-run the <code>CreateCluster</code> tool. 

@advanced_1098_h3
#Detect Which Cluster Instances are Running

@advanced_1099_p
# To find out which cluster nodes are currently running, execute the following SQL statement: 

@advanced_1100_p
# If the result is <code>''</code> (two single quotes), then the cluster mode is disabled. Otherwise, the list of servers is returned, enclosed in single quote. Example: <code>'server1:9191,server2:9191'</code>. 

@advanced_1101_h3
クラスタリングアルゴリズムと制限

@advanced_1102_p
# Read-only queries are only executed against the first cluster node, but all other statements are executed against all nodes. There is currently no load balancing made to avoid problems with transactions. The following functions may yield different results on different cluster nodes and must be executed with care: <code>RANDOM_UUID(), SECURE_RAND(), SESSION_ID(), MEMORY_FREE(), MEMORY_USED(), CSVREAD(), CSVWRITE(), RAND()</code> [when not using a seed]. Those functions should not be used directly in modifying statements (for example <code>INSERT, UPDATE, MERGE</code>). However, they can be used in read-only statements and the result can then be used for modifying statements. 

@advanced_1103_p
# When using the cluster modes, result sets are read fully in memory by the client, so that there is no problem if the server dies that executed the query. Result sets must fit in memory on the client side. 

@advanced_1104_h2
2フェーズコミット

@advanced_1105_p
# The two phase commit protocol is supported. 2-phase-commit works as follows: 

@advanced_1106_li
#Autocommit needs to be switched off 

@advanced_1107_li
#A transaction is started, for example by inserting a row 

@advanced_1108_li
#The transaction is marked 'prepared' by executing the SQL statement <code>PREPARE COMMIT transactionName</code> 

@advanced_1109_li
#The transaction can now be committed or rolled back 

@advanced_1110_li
#If a problem occurs before the transaction was successfully committed or rolled back (for example because a network problem occurred), the transaction is in the state 'in-doubt' 

@advanced_1111_li
#When re-connecting to the database, the in-doubt transactions can be listed with <code>SELECT * FROM INFORMATION_SCHEMA.IN_DOUBT</code> 

@advanced_1112_li
#Each transaction in this list must now be committed or rolled back by executing <code>COMMIT TRANSACTION transactionName</code> or <code>ROLLBACK TRANSACTION transactionName</code> 

@advanced_1113_li
#The database needs to be closed and re-opened to apply the changes 

@advanced_1114_h2
互換性

@advanced_1115_p
# This database is (up to a certain point) compatible to other databases such as HSQLDB, MySQL and PostgreSQL. There are certain areas where H2 is incompatible. 

@advanced_1116_h3
オートコミットがONの時のトランザクションコミット

@advanced_1117_p
# At this time, this database engine commits a transaction (if autocommit is switched on) just before returning the result. For a query, this means the transaction is committed even before the application scans through the result set, and before the result set is closed. Other database engines may commit the transaction in this case when the result set is closed. 

@advanced_1118_h3
キーワード / 予約語

@advanced_1119_p
# There is a list of keywords that can't be used as identifiers (table names, column names and so on), unless they are quoted (surrounded with double quotes). The list is currently: 

@advanced_1120_code
# CROSS, CURRENT_DATE, CURRENT_TIME, CURRENT_TIMESTAMP, DISTINCT, EXCEPT, EXISTS, FALSE, FOR, FROM, FULL, GROUP, HAVING, INNER, INTERSECT, IS, JOIN, LIKE, LIMIT, MINUS, NATURAL, NOT, NULL, ON, ORDER, PRIMARY, ROWNUM, SELECT, SYSDATE, SYSTIME, SYSTIMESTAMP, TODAY, TRUE, UNION, UNIQUE, WHERE 

@advanced_1121_p
# Certain words of this list are keywords because they are functions that can be used without '()' for compatibility, for example <code>CURRENT_TIMESTAMP</code>. 

@advanced_1122_h2
#Standards Compliance

@advanced_1123_p
# This database tries to be as much standard compliant as possible. For the SQL language, ANSI/ISO is the main standard. There are several versions that refer to the release date: SQL-92, SQL:1999, and SQL:2003. Unfortunately, the standard documentation is not freely available. Another problem is that important features are not standardized. Whenever this is the case, this database tries to be compatible to other databases. 

@advanced_1124_h2
Windowsサービスとして実行する

@advanced_1125_p
# Using a native wrapper / adapter, Java applications can be run as a Windows Service. There are various tools available to do that. The Java Service Wrapper from <a href="http://wrapper.tanukisoftware.org">Tanuki Software, Inc.</a> is included in the installation. Batch files are provided to install, start, stop and uninstall the H2 Database Engine Service. This service contains the TCP Server and the H2 Console web application. The batch files are located in the directory <code>h2/service</code>. 

@advanced_1126_h3
サービスをインストールする

@advanced_1127_p
# The service needs to be registered as a Windows Service first. To do that, double click on <code>1_install_service.bat</code>. If successful, a command prompt window will pop up and disappear immediately. If not, a message will appear. 

@advanced_1128_h3
サービスを起動する

@advanced_1129_p
# You can start the H2 Database Engine Service using the service manager of Windows, or by double clicking on <code>2_start_service.bat</code>. Please note that the batch file does not print an error message if the service is not installed. 

@advanced_1130_h3
H2コンソールに接続する

@advanced_1131_p
# After installing and starting the service, you can connect to the H2 Console application using a browser. Double clicking on <code>3_start_browser.bat</code> to do that. The default port (8082) is hard coded in the batch file. 

@advanced_1132_h3
サービスを終了する

@advanced_1133_p
# To stop the service, double click on <code>4_stop_service.bat</code>. Please note that the batch file does not print an error message if the service is not installed or started. 

@advanced_1134_h3
サービスのアンインストール

@advanced_1135_p
# To uninstall the service, double click on <code>5_uninstall_service.bat</code>. If successful, a command prompt window will pop up and disappear immediately. If not, a message will appear. 

@advanced_1136_h2
ODBCドライバ

@advanced_1137_p
# This database does not come with its own ODBC driver at this time, but it supports the PostgreSQL network protocol. Therefore, the PostgreSQL ODBC driver can be used. Support for the PostgreSQL network protocol is quite new and should be viewed as experimental. It should not be used for production applications. 

@advanced_1138_p
# To use the PostgreSQL ODBC driver on 64 bit versions of Windows, first run <code>c:/windows/syswow64/odbcad32.exe</code>. At this point you set up your DSN just like you would on any other system. See also: <a href="http://archives.postgresql.org/pgsql-odbc/2005-09/msg00125.php">Re: ODBC Driver on Windows 64 bit</a> 

@advanced_1139_h3
ODBCインストール

@advanced_1140_p
# First, the ODBC driver must be installed. Any recent PostgreSQL ODBC driver should work, however version 8.2 (<code>psqlodbc-08_02*</code>) or newer is recommended. The Windows version of the PostgreSQL ODBC driver is available at <a href="http://www.postgresql.org/ftp/odbc/versions/msi">http://www.postgresql.org/ftp/odbc/versions/msi</a>. 

@advanced_1141_h3
サーバーの起動

@advanced_1142_p
# After installing the ODBC driver, start the H2 Server using the command line: 

@advanced_1143_p
# The PG Server (PG for PostgreSQL protocol) is started as well. By default, databases are stored in the current working directory where the server is started. Use <code>-baseDir</code> to save databases in another directory, for example the user home directory: 

@advanced_1144_p
# The PG server can be started and stopped from within a Java application as follows: 

@advanced_1145_p
# By default, only connections from localhost are allowed. To allow remote connections, use <code>-pgAllowOthers</code> when starting the server. 

@advanced_1146_h3
ODBC設定

@advanced_1147_p
# After installing the driver, a new Data Source must be added. In Windows, run <code>odbcad32.exe</code> to open the Data Source Administrator. Then click on 'Add...' and select the PostgreSQL Unicode driver. Then click 'Finish'. You will be able to change the connection properties: 

@advanced_1148_th
プロパティ

@advanced_1149_th
例

@advanced_1150_th
コメント

@advanced_1151_td
Data Source

@advanced_1152_td
H2 Test

@advanced_1153_td
ODBCデータソースの名称

@advanced_1154_td
Database

@advanced_1155_td
test

@advanced_1156_td
# The database name. Only simple names are supported at this time; 

@advanced_1157_td
# relative or absolute path are not supported in the database name. 

@advanced_1158_td
# By default, the database is stored in the current working directory 

@advanced_1159_td
# where the Server is started except when the -baseDir setting is used. 

@advanced_1160_td
# The name must be at least 3 characters. 

@advanced_1161_td
Server

@advanced_1162_td
localhost

@advanced_1163_td
サーバー名、またはIPアドレス

@advanced_1164_td
デフォルトでは、リモート接続のみ許可されています。

@advanced_1165_td
User Name

@advanced_1166_td
sa

@advanced_1167_td
データベースのユーザー名

@advanced_1168_td
SSL Mode

@advanced_1169_td
disabled

@advanced_1170_td
現時点で、SSLはサポートされていません。

@advanced_1171_td
Port

@advanced_1172_td
5435

@advanced_1173_td
PGサーバーが傾聴しているポート

@advanced_1174_td
Password

@advanced_1175_td
sa

@advanced_1176_td
データベースパスワード

@advanced_1177_p
# To improve performance, please enable 'server side prepare' under Options / Datasource / Page 2 / Server side prepare. 

@advanced_1178_p
# Afterwards, you may use this data source. 

@advanced_1179_h3
PGプロトコルサポートの制限

@advanced_1180_p
# At this time, only a subset of the PostgreSQL network protocol is implemented. Also, there may be compatibility problems on the SQL level, with the catalog, or with text encoding. Problems are fixed as they are found. Currently, statements can not be canceled when using the PG protocol. 

@advanced_1181_p
# PostgreSQL ODBC Driver Setup requires a database password; that means it is not possible to connect to H2 databases without password. This is a limitation of the ODBC driver. 

@advanced_1182_h3
セキュリティ考慮

@advanced_1183_p
# Currently, the PG Server does not support challenge response or encrypt passwords. This may be a problem if an attacker can listen to the data transferred between the ODBC driver and the server, because the password is readable to the attacker. Also, it is currently not possible to use encrypted SSL connections. Therefore the ODBC driver should not be used where security is important. 

@advanced_1184_h2
#Using H2 in Microsoft .NET

@advanced_1185_p
# The database can be used from Microsoft .NET even without using Java, by using IKVM.NET. You can access a H2 database on .NET using the JDBC API, or using the ADO.NET interface. 

@advanced_1186_h3
#Using the ADO.NET API on .NET

@advanced_1187_p
# An implementation of the ADO.NET interface is available in the open source project <a href="http://code.google.com/p/h2sharp">H2Sharp</a>. 

@advanced_1188_h3
#Using the JDBC API on .NET

@advanced_1189_li
#Install the .NET Framework from <a href="http://www.microsoft.com">Microsoft</a>. Mono has not yet been tested. 

@advanced_1190_li
#Install <a href="http://www.ikvm.net">IKVM.NET</a>. 

@advanced_1191_li
#Copy the <code>h2*.jar</code> file to <code>ikvm/bin</code> 

@advanced_1192_li
#Run the H2 Console using: <code>ikvm -jar h2*.jar</code> 

@advanced_1193_li
#Convert the H2 Console to an <code>.exe</code> file using: <code>ikvmc -target:winexe h2*.jar</code>. You may ignore the warnings. 

@advanced_1194_li
#Create a <code>.dll</code> file using (change the version accordingly): <code>ikvmc.exe -target:library -version:1.0.69.0 h2*.jar</code> 

@advanced_1195_p
# If you want your C# application use H2, you need to add the <code>h2.dll</code> and the <code>IKVM.OpenJDK.ClassLibrary.dll</code> to your C# solution. Here some sample code: 

@advanced_1196_h2
ACID

@advanced_1197_p
# In the database world, ACID stands for: 

@advanced_1198_li
#Atomicity: transactions must be atomic, meaning either all tasks are performed or none. 

@advanced_1199_li
#Consistency: all operations must comply with the defined constraints. 

@advanced_1200_li
#Isolation: transactions must be isolated from each other. 

@advanced_1201_li
#Durability: committed transaction will not be lost. 

@advanced_1202_h3
Atomicity (原子性)

@advanced_1203_p
# Transactions in this database are always atomic. 

@advanced_1204_h3
Consistency (一貫性)

@advanced_1205_p
# By default, this database is always in a consistent state. Referential integrity rules are enforced except when explicitly disabled. 

@advanced_1206_h3
Isolation (独立性 / 分離性)

@advanced_1207_p
# For H2, as with most other database systems, the default isolation level is 'read committed'. This provides better performance, but also means that transactions are not completely isolated. H2 supports the transaction isolation levels 'serializable', 'read committed', and 'read uncommitted'. 

@advanced_1208_h3
Durability (永続性)

@advanced_1209_p
# This database does not guarantee that all committed transactions survive a power failure. Tests show that all databases sometimes lose transactions on power failure (for details, see below). Where losing transactions is not acceptable, a laptop or UPS (uninterruptible power supply) should be used. If durability is required for all possible cases of hardware failure, clustering should be used, such as the H2 clustering mode. 

@advanced_1210_h2
永続性問題

@advanced_1211_p
# Complete durability means all committed transaction survive a power failure. Some databases claim they can guarantee durability, but such claims are wrong. A durability test was run against H2, HSQLDB, PostgreSQL, and Derby. All of those databases sometimes lose committed transactions. The test is included in the H2 download, see <code>org.h2.test.poweroff.Test</code>. 

@advanced_1212_h3
永続性を実現する (しない) 方法

@advanced_1213_p
# Making sure that committed transactions are not lost is more complicated than it seems first. To guarantee complete durability, a database must ensure that the log record is on the hard drive before the commit call returns. To do that, databases use different methods. One is to use the 'synchronous write' file access mode. In Java, <code>RandomAccessFile</code> supports the modes <code>rws</code> and <code>rwd</code>: 

@advanced_1214_code
#rwd

@advanced_1215_li
#: every update to the file's content is written synchronously to the underlying storage device. 

@advanced_1216_code
#rws

@advanced_1217_li
#: in addition to <code>rwd</code>, every update to the metadata is written synchronously.

@advanced_1218_p
# A test (<code>org.h2.test.poweroff.TestWrite</code>) with one of those modes achieves around 50 thousand write operations per second. Even when the operating system write buffer is disabled, the write rate is around 50 thousand operations per second. This feature does not force changes to disk because it does not flush all buffers. The test updates the same byte in the file again and again. If the hard drive was able to write at this rate, then the disk would need to make at least 50 thousand revolutions per second, or 3 million RPM (revolutions per minute). There are no such hard drives. The hard drive used for the test is about 7200 RPM, or about 120 revolutions per second. There is an overhead, so the maximum write rate must be lower than that. 

@advanced_1219_p
# Calling <code>fsync</code> flushes the buffers. There are two ways to do that in Java: 

@advanced_1220_code
#FileDescriptor.sync()

@advanced_1221_li
#. The documentation says that this forces all system buffers to synchronize with the underlying device. This method is supposed to return after all in-memory modified copies of buffers associated with this file descriptor have been written to the physical medium. 

@advanced_1222_code
#FileChannel.force()

@advanced_1223_li
# (since JDK 1.4). This method is supposed to force any updates to this channel's file to be written to the storage device that contains it. 

@advanced_1224_p
# By default, MySQL calls <code>fsync</code> for each commit. When using one of those methods, only around 60 write operations per second can be achieved, which is consistent with the RPM rate of the hard drive used. Unfortunately, even when calling <code>FileDescriptor.sync()</code> or <code>FileChannel.force()</code>, data is not always persisted to the hard drive, because most hard drives do not obey <code>fsync()</code>: see <a href="http://hardware.slashdot.org/article.pl?sid=05/05/13/0529252">Your Hard Drive Lies to You</a>. In Mac OS X, <code>fsync</code> does not flush hard drive buffers. See <a href="http://lists.apple.com/archives/darwin-dev/2005/Feb/msg00072.html">Bad fsync?</a>. So the situation is confusing, and tests prove there is a problem. 

@advanced_1225_p
# Trying to flush hard drive buffers is hard, and if you do the performance is very bad. First you need to make sure that the hard drive actually flushes all buffers. Tests show that this can not be done in a reliable way. Then the maximum number of transactions is around 60 per second. Because of those reasons, the default behavior of H2 is to delay writing committed transactions. 

@advanced_1226_p
# In H2, after a power failure, a bit more than one second of committed transactions may be lost. To change the behavior, use <code>SET WRITE_DELAY</code> and <code>CHECKPOINT SYNC</code>. Most other databases support commit delay as well. In the performance comparison, commit delay was used for all databases that support it. 

@advanced_1227_h3
永続性テストを実行する

@advanced_1228_p
# To test the durability / non-durability of this and other databases, you can use the test application in the package <code>org.h2.test.poweroff</code>. Two computers with network connection are required to run this test. One computer just listens, while the test application is run (and power is cut) on the other computer. The computer with the listener application opens a TCP/IP port and listens for an incoming connection. The second computer first connects to the listener, and then created the databases and starts inserting records. The connection is set to 'autocommit', which means after each inserted record a commit is performed automatically. Afterwards, the test computer notifies the listener that this record was inserted successfully. The listener computer displays the last inserted record number every 10 seconds. Now, switch off the power manually, then restart the computer, and run the application again. You will find out that in most cases, none of the databases contains all the records that the listener computer knows about. For details, please consult the source code of the listener and test application. 

@advanced_1229_h2
リカバーツールを使用する

@advanced_1230_p
# The <code>Recover</code> tool can be used to extract the contents of a database file, even if the database is corrupted. It also extracts the content of the transaction log and large objects (CLOB or BLOB). To run the tool, type on the command line: 

@advanced_1231_p
# For each database in the current directory, a text file will be created. This file contains raw insert statements (for the data) and data definition (DDL) statements to recreate the schema of the database. This file can be executed using the <code>RunScript</code> tool or a <code>RUNSCRIPT FROM</code> SQL statement. The script includes at least one <code>CREATE USER</code> statement. If you run the script against a database that was created with the same user, or if there are conflicting users, running the script will fail. Consider running the script against a database that was created with a user name that is not in the script. 

@advanced_1232_p
# The <code>Recover</code> tool creates a SQL script from database file. It also processes the transaction log. 

@advanced_1233_h2
ファイルロックプロトコル

@advanced_1234_p
# Whenever a database is opened, a lock file is created to signal other processes that the database is in use. If the database is closed, or if the process that opened the database terminates, this lock file is deleted. 

@advanced_1235_p
# In special cases (if the process did not terminate normally, for example because there was a power failure), the lock file is not deleted by the process that created it. That means the existence of the lock file is not a safe protocol for file locking. However, this software uses a challenge-response protocol to protect the database files. There are two methods (algorithms) implemented to provide both security (that is, the same database files cannot be opened by two processes at the same time) and simplicity (that is, the lock file does not need to be deleted manually by the user). The two methods are 'file method' and 'socket methods'. 

@advanced_1236_p
# The file locking protocols have the following limitation: if a shared file system is used, and the machine with the lock owner is sent to sleep (standby or hibernate), another machine may take over. If the machine that originally held the lock wakes up, the database may become corrupt. If this situation can occur, the application must ensure the database is closed when the application is put to sleep. 

@advanced_1237_h3
ファイルロックメソッド "File"

@advanced_1238_p
# The default method for database file locking is the 'File Method'. The algorithm is: 

@advanced_1239_li
#If the lock file does not exist, it is created (using the atomic operation <code>File.createNewFile</code>). Then, the process waits a little bit (20 ms) and checks the file again. If the file was changed during this time, the operation is aborted. This protects against a race condition when one process deletes the lock file just after another one create it, and a third process creates the file again. It does not occur if there are only two writers. 

@advanced_1240_li
# If the file can be created, a random number is inserted together with the locking method ('file'). Afterwards, a watchdog thread is started that checks regularly (every second once by default) if the file was deleted or modified by another (challenger) thread / process. Whenever that occurs, the file is overwritten with the old data. The watchdog thread runs with high priority so that a change to the lock file does not get through undetected even if the system is very busy. However, the watchdog thread does use very little resources (CPU time), because it waits most of the time. Also, the watchdog only reads from the hard disk and does not write to it. 

@advanced_1241_li
# If the lock file exists and was recently modified, the process waits for some time (up to two seconds). If it was still changed, an exception is thrown (database is locked). This is done to eliminate race conditions with many concurrent writers. Afterwards, the file is overwritten with a new version (challenge). After that, the thread waits for 2 seconds. If there is a watchdog thread protecting the file, he will overwrite the change and this process will fail to lock the database. However, if there is no watchdog thread, the lock file will still be as written by this thread. In this case, the file is deleted and atomically created again. The watchdog thread is started in this case and the file is locked. 

@advanced_1242_p
# This algorithm is tested with over 100 concurrent threads. In some cases, when there are many concurrent threads trying to lock the database, they block each other (meaning the file cannot be locked by any of them) for some time. However, the file never gets locked by two threads at the same time. However using that many concurrent threads / processes is not the common use case. Generally, an application should throw an error to the user if it cannot open a database, and not try again in a (fast) loop. 

@advanced_1243_h3
ファイルロックメソッド "Socket"

@advanced_1244_p
# There is a second locking mechanism implemented, but disabled by default. To use it, append <code>;FILE_LOCK=SOCKET</code> to the database URL. The algorithm is: 

@advanced_1245_li
#If the lock file does not exist, it is created. Then a server socket is opened on a defined port, and kept open. The port and IP address of the process that opened the database is written into the lock file. 

@advanced_1246_li
#If the lock file exists, and the lock method is 'file', then the software switches to the 'file' method. 

@advanced_1247_li
#If the lock file exists, and the lock method is 'socket', then the process checks if the port is in use. If the original process is still running, the port is in use and this process throws an exception (database is in use). If the original process died (for example due to a power failure, or abnormal termination of the virtual machine), then the port was released. The new process deletes the lock file and starts again. 

@advanced_1248_p
# This method does not require a watchdog thread actively polling (reading) the same file every second. The problem with this method is, if the file is stored on a network share, two processes (running on different computers) could still open the same database files, if they do not have a direct TCP/IP connection. 

@advanced_1249_h2
#File Locking Method 'Serialized'

@advanced_1250_p
# This locking mode allows to open multiple connections to the same database. The connections may be opened from multiple processes and from different computers. When writing to the database, access is automatically synchronized internally. Write operations are slower than when using the server mode, and concurrency is relatively poor. The advantage of this mode is that there is no need to start a server. 

@advanced_1251_p
# To enable this feature, append <code>;FILE_LOCK=SERIALIZED</code> to the database URL. 

@advanced_1252_p
# This feature is relatively new. When using it for production, please ensure your use case is well tested (if possible with automated test cases). 

@advanced_1253_h2
SQLインジェクションに対する防御

@advanced_1254_h3
SQLインジェクションとは

@advanced_1255_p
# This database engine provides a solution for the security vulnerability known as 'SQL Injection'. Here is a short description of what SQL injection means. Some applications build SQL statements with embedded user input such as: 

@advanced_1256_p
# If this mechanism is used anywhere in the application, and user input is not correctly filtered or encoded, it is possible for a user to inject SQL functionality or statements by using specially built input such as (in this example) this password: <code>' OR ''='</code>. In this case the statement becomes: 

@advanced_1257_p
# Which is always true no matter what the password stored in the database is. For more information about SQL Injection, see <a href="#glossary_links">Glossary and Links</a>. 

@advanced_1258_h3
リテラルを無効にする

@advanced_1259_p
# SQL Injection is not possible if user input is not directly embedded in SQL statements. A simple solution for the problem above is to use a prepared statement: 

@advanced_1260_p
# This database provides a way to enforce usage of parameters when passing user input to the database. This is done by disabling embedded literals in SQL statements. To do this, execute the statement: 

@advanced_1261_p
# Afterwards, SQL statements with text and number literals are not allowed any more. That means, SQL statement of the form <code>WHERE NAME='abc'</code> or <code>WHERE CustomerId=10</code> will fail. It is still possible to use prepared statements and parameters as described above. Also, it is still possible to generate SQL statements dynamically, and use the Statement API, as long as the SQL statements do not include literals. There is also a second mode where number literals are allowed: <code>SET ALLOW_LITERALS NUMBERS</code>. To allow all literals, execute <code>SET ALLOW_LITERALS ALL</code> (this is the default setting). Literals can only be enabled or disabled by an administrator. 

@advanced_1262_h3
定数を使用する

@advanced_1263_p
# Disabling literals also means disabling hard-coded 'constant' literals. This database supports defining constants using the <code>CREATE CONSTANT</code> command. Constants can be defined only when literals are enabled, but used even when literals are disabled. To avoid name clashes with column names, constants can be defined in other schemas: 

@advanced_1264_p
# Even when literals are enabled, it is better to use constants instead of hard-coded number or text literals in queries or views. With constants, typos are found at compile time, the source code is easier to understand and change. 

@advanced_1265_h3
ZERO() 関数を使用する

@advanced_1266_p
# It is not required to create a constant for the number 0 as there is already a built-in function <code>ZERO()</code>: 

@advanced_1267_h2
#Protection against Remote Access

@advanced_1268_p
# By default this database does not allow connections from other machines when starting the H2 Console, the TCP server, or the PG server. Remote access can be enabled using the command line options <code>-webAllowOthers, -tcpAllowOthers, -pgAllowOthers</code>. If you enable remote access, please also consider using the options <code>-baseDir, -ifExists</code>, so that remote users can not create new databases or access existing databases with weak passwords. When using the option <code>-baseDir</code>, only databases within that directory may be accessed. Ensure the existing accessible databases are protected using strong passwords. 

@advanced_1269_h2
#Restricting Class Loading and Usage

@advanced_1270_p
# By default there is no restriction on loading classes and executing Java code for admins. That means an admin may call system functions such as <code>System.setProperty</code> by executing: 

@advanced_1271_p
# To restrict users (including admins) from loading classes and executing code, the list of allowed classes can be set in the system property <code>h2.allowedClasses</code> in the form of a comma separated list of classes or patterns (items ending with <code>*</code>). By default all classes are allowed. Example: 

@advanced_1272_p
# This mechanism is used for all user classes, including database event listeners, trigger classes, user-defined functions, user-defined aggregate functions, and JDBC driver classes (with the exception of the H2 driver) when using the H2 Console. 

@advanced_1273_h2
セキュリティプロトコル

@advanced_1274_p
# The following paragraphs document the security protocols used in this database. These descriptions are very technical and only intended for security experts that already know the underlying security primitives. 

@advanced_1275_h3
ユーザーパスワードの暗号化

@advanced_1276_p
# When a user tries to connect to a database, the combination of user name, @, and password are hashed using SHA-256, and this hash value is transmitted to the database. This step does not protect against an attacker that re-uses the value if he is able to listen to the (unencrypted) transmission between the client and the server. But, the passwords are never transmitted as plain text, even when using an unencrypted connection between client and server. That means if a user reuses the same password for different things, this password is still protected up to some point. See also 'RFC 2617 - HTTP Authentication: Basic and Digest Access Authentication' for more information. 

@advanced_1277_p
# When a new database or user is created, a new random salt value is generated. The size of the salt is 64 bits. Using the random salt reduces the risk of an attacker pre-calculating hash values for many different (commonly used) passwords. 

@advanced_1278_p
# The combination of user-password hash value (see above) and salt is hashed using SHA-256. The resulting value is stored in the database. When a user tries to connect to the database, the database combines user-password hash value with the stored salt value and calculates the hash value. Other products use multiple iterations (hash the hash value again and again), but this is not done in this product to reduce the risk of denial of service attacks (where the attacker tries to connect with bogus passwords, and the server spends a lot of time calculating the hash value for each password). The reasoning is: if the attacker has access to the hashed passwords, he also has access to the data in plain text, and therefore does not need the password any more. If the data is protected by storing it on another computer and only accessible remotely, then the iteration count is not required at all. 

@advanced_1279_h3
ファイル暗号化

@advanced_1280_p
# The database files can be encrypted using two different algorithms: AES-128 and XTEA (using 32 rounds). The reasons for supporting XTEA is performance (XTEA is about twice as fast as AES) and to have an alternative algorithm if AES is suddenly broken. 

@advanced_1281_p
# When a user tries to connect to an encrypted database, the combination of <code>file@</code> and the file password is hashed using SHA-256. This hash value is transmitted to the server. 

@advanced_1282_p
# When a new database file is created, a new cryptographically secure random salt value is generated. The size of the salt is 64 bits. The combination of the file password hash and the salt value is hashed 1024 times using SHA-256. The reason for the iteration is to make it harder for an attacker to calculate hash values for common passwords. 

@advanced_1283_p
# The resulting hash value is used as the key for the block cipher algorithm (AES-128 or XTEA with 32 rounds). Then, an initialization vector (IV) key is calculated by hashing the key again using SHA-256. This is to make sure the IV is unknown to the attacker. The reason for using a secret IV is to protect against watermark attacks. 

@advanced_1284_p
# Before saving a block of data (each block is 8 bytes long), the following operations are executed: first, the IV is calculated by encrypting the block number with the IV key (using the same block cipher algorithm). This IV is combined with the plain text using XOR. The resulting data is encrypted using the AES-128 or XTEA algorithm. 

@advanced_1285_p
# When decrypting, the operation is done in reverse. First, the block is decrypted using the key, and then the IV is calculated combined with the decrypted text using XOR. 

@advanced_1286_p
# Therefore, the block cipher mode of operation is CBC (cipher-block chaining), but each chain is only one block long. The advantage over the ECB (electronic codebook) mode is that patterns in the data are not revealed, and the advantage over multi block CBC is that flipped cipher text bits are not propagated to flipped plaintext bits in the next block. 

@advanced_1287_p
# Database encryption is meant for securing the database while it is not in use (stolen laptop and so on). It is not meant for cases where the attacker has access to files while the database is in use. When he has write access, he can for example replace pieces of files with pieces of older versions and manipulate data like this. 

@advanced_1288_p
# File encryption slows down the performance of the database engine. Compared to unencrypted mode, database operations take about 2.2 times longer when using XTEA, and 2.5 times longer using AES (embedded mode). 

@advanced_1289_h3
#Wrong Password / User Name Delay

@advanced_1290_p
# To protect against remote brute force password attacks, the delay after each unsuccessful login gets double as long. Use the system properties <code>h2.delayWrongPasswordMin</code> and <code>h2.delayWrongPasswordMax</code> to change the minimum (the default is 250 milliseconds) or maximum delay (the default is 4000 milliseconds, or 4 seconds). The delay only applies for those using the wrong password. Normally there is no delay for a user that knows the correct password, with one exception: after using the wrong password, there is a delay of up to (randomly distributed) the same delay as for a wrong password. This is to protect against parallel brute force attacks, so that an attacker needs to wait for the whole delay. Delays are synchronized. This is also required to protect against parallel attacks. 

@advanced_1291_p
# There is only one exception message for both wrong user and for wrong password, to make it harder to get the list of user names. It is not possible from the stack trace to see if the user name was wrong or the password. 

@advanced_1292_h3
HTTPS 接続

@advanced_1293_p
# The web server supports HTTP and HTTPS connections using <code>SSLServerSocket</code>. There is a default self-certified certificate to support an easy starting point, but custom certificates are supported as well. 

@advanced_1294_h2
SSL/TLS 接続

@advanced_1295_p
# Remote SSL/TLS connections are supported using the Java Secure Socket Extension (<code>SSLServerSocket, SSLSocket</code>). By default, anonymous SSL is enabled. The default cipher suite is <code>SSL_DH_anon_WITH_RC4_128_MD5</code>. 

@advanced_1296_p
# To use your own keystore, set the system properties <code>javax.net.ssl.keyStore</code> and <code>javax.net.ssl.keyStorePassword</code> before starting the H2 server and client. See also <a href="http://java.sun.com/javase/6/docs/technotes/guides/security/jsse/JSSERefGuide.html#CustomizingStores"> Customizing the Default Key and Trust Stores, Store Types, and Store Passwords</a> for more information. 

@advanced_1297_p
# To disable anonymous SSL, set the system property <code>h2.enableAnonymousSSL</code> to false. 

@advanced_1298_h2
汎用一意識別子 (UUID)

@advanced_1299_p
# This database supports UUIDs. Also supported is a function to create new UUIDs using a cryptographically strong pseudo random number generator. With random UUIDs, the chance of two having the same value can be calculated using the probability theory. See also 'Birthday Paradox'. Standardized randomly generated UUIDs have 122 random bits. 4 bits are used for the version (Randomly generated UUID), and 2 bits for the variant (Leach-Salz). This database supports generating such UUIDs using the built-in function <code>RANDOM_UUID()</code>. Here is a small program to estimate the probability of having two identical UUIDs after generating a number of values: 

@advanced_1300_p
# Some values are: 

@advanced_1301_th
#Number of UUIs

@advanced_1302_th
#Probability of Duplicates

@advanced_1303_td
#2^36=68'719'476'736

@advanced_1304_td
#0.000'000'000'000'000'4

@advanced_1305_td
#2^41=2'199'023'255'552

@advanced_1306_td
#0.000'000'000'000'4

@advanced_1307_td
#2^46=70'368'744'177'664

@advanced_1308_td
#0.000'000'000'4

@advanced_1309_p
# To help non-mathematicians understand what those numbers mean, here a comparison: one's annual risk of being hit by a meteorite is estimated to be one chance in 17 billion, that means the probability is about 0.000'000'000'06. 

@advanced_1310_h2
システムプロパティから読み込まれた設定

@advanced_1311_p
# Some settings of the database can be set on the command line using <code>-DpropertyName=value</code>. It is usually not required to change those settings manually. The settings are case sensitive. Example: 

@advanced_1312_p
# The current value of the settings can be read in the table <code>INFORMATION_SCHEMA.SETTINGS</code>. 

@advanced_1313_p
# For a complete list of settings, see <a href="../javadoc/org/h2/constant/SysProperties.html">SysProperties</a>. 

@advanced_1314_h2
#Setting the Server Bind Address

@advanced_1315_p
# Usually server sockets accept connections on any/all local addresses. This may be a problem on multi-homed hosts. To bind only to one address, use the system property <code>h2.bindAddress</code>. This setting is used for both regular server sockets and for SSL server sockets. IPv4 and IPv6 address formats are supported. 

@advanced_1316_h2
#Pluggable File System

@advanced_1317_p
# This database supports a pluggable file system API. The file system implementation is selected using a file name prefix. The following file systems are included: 

@advanced_1318_code
#zip:

@advanced_1319_li
# read-only zip-file based file system. Format: <code>zip:/zipFileName!/fileName</code>. 

@advanced_1320_code
#nio:

@advanced_1321_li
# file system that uses <code>FileChannel</code> instead of <code>RandomAccessFile</code> (faster in some operating systems). 

@advanced_1322_code
#nioMapped:

@advanced_1323_li
# file system that uses memory mapped files (faster in some operating systems). 

@advanced_1324_code
#split:

@advanced_1325_li
# file system that splits files in 1 GB files (stackable with other file systems). 

@advanced_1326_code
#memFS:

@advanced_1327_li
# in-memory file system (slower than mem; experimental; mainly used for testing the database engine itself). 

@advanced_1328_code
#memLZF:

@advanced_1329_li
# compressing in-memory file system (slower than memFS but uses less memory; experimental; mainly used for testing the database engine itself). 

@advanced_1330_p
# As an example, to use the the <code>nio</code> file system, use the following database URL: <code>jdbc:h2:nio:~/test</code>. 

@advanced_1331_p
# To register a new file system, extend the classes <code>org.h2.store.fs.FileSystem, FileObject</code>, and call the method <code>FileSystem.register</code> before using it. 

@advanced_1332_h2
#Limits and Limitations

@advanced_1333_p
# This database has the following known limitations: 

@advanced_1334_li
#Database file size limits (excluding BLOB and CLOB data): With the default storage mechanism, the maximum file size is currently 256 GB for the data, and 256 GB for the index. With the page store (experimental): 4 TB or higher. 

@advanced_1335_li
#BLOB and CLOB size limit: every CLOB or BLOB can be up to 256 GB. 

@advanced_1336_li
#The maximum file size for FAT or FAT32 file systems is 4 GB. That means when using FAT or FAT32, the limit is 4 GB for the data. This is the limitation of the file system. The database does provide a workaround for this problem, it is to use the file name prefix <code>split:</code>. In that case files are split into files of 1 GB by default. An example database URL is: <code>jdbc:h2:split:~/test</code>. 

@advanced_1337_li
#The maximum number of rows per table is 2'147'483'648. 

@advanced_1338_li
#Main memory requirements: The larger the database, the more main memory is required. With the default storage mechanism, the minimum main memory required for a 12 GB database is around 240 MB. With the page store (experimental), the minimum main memory required is much lower, around 1 MB for each 8 GB database file size. 

@advanced_1339_li
#Limit on the complexity of SQL statements. Statements of the following form will result in a stack overflow exception: 

@advanced_1340_li
#There is no limit for the following entities, except the memory and storage capacity: maximum identifier length (table name, column name, and so on); maximum number of tables, columns, indexes, triggers, and other database objects; maximum statement length, number of parameters per statement, tables per statement, expressions in order by, group by, having, and so on; maximum rows per query; maximum columns per table, columns per index, indexes per table, lob columns per table, and so on; maximum row length, index row length, select row length; maximum length of a varchar column, decimal column, literal in a statement. 

@advanced_1341_li
#For limitations on data types, see the documentation of the respective Java data type or the data type documentation of this database. 

@advanced_1342_h2
用語集とリンク

@advanced_1343_th
用語

@advanced_1344_th
説明

@advanced_1345_td
AES-128

@advanced_1346_td
#A block encryption algorithm. See also: <a href="http://en.wikipedia.org/wiki/Advanced_Encryption_Standard">Wikipedia: AES</a>

@advanced_1347_td
Birthday Paradox

@advanced_1348_td
#Describes the higher than expected probability that two persons in a room have the same birthday. Also valid for randomly generated UUIDs. See also: <a href="http://en.wikipedia.org/wiki/Birthday_paradox">Wikipedia: Birthday Paradox</a>

@advanced_1349_td
Digest

@advanced_1350_td
#Protocol to protect a password (but not to protect data). See also: <a href="http://www.faqs.org/rfcs/rfc2617.html">RFC 2617: HTTP Digest Access Authentication</a>

@advanced_1351_td
GCJ

@advanced_1352_td
#Compiler for Java. <a href="http://gcc.gnu.org/java">GNU Compiler for the Java</a> and <a href="http://www.dobysoft.com/products/nativej">NativeJ (commercial)</a>

@advanced_1353_td
HTTPS

@advanced_1354_td
#A protocol to provide security to HTTP connections. See also: <a href="http://www.ietf.org/rfc/rfc2818.txt">RFC 2818: HTTP Over TLS</a>

@advanced_1355_td
Modes of Operation

@advanced_1356_a
#Wikipedia: Block cipher modes of operation

@advanced_1357_td
Salt

@advanced_1358_td
#Random number to increase the security of passwords. See also: <a href="http://en.wikipedia.org/wiki/Key_derivation_function">Wikipedia: Key derivation function</a>

@advanced_1359_td
SHA-256

@advanced_1360_td
#A cryptographic one-way hash function. See also: <a href="http://en.wikipedia.org/wiki/SHA_family">Wikipedia: SHA hash functions</a>

@advanced_1361_td
SQLインジェクション

@advanced_1362_td
#A security vulnerability where an application embeds SQL statements or expressions in user input. See also: <a href="http://en.wikipedia.org/wiki/SQL_injection">Wikipedia: SQL Injection</a>

@advanced_1363_td
Watermark Attack (透かし攻撃)

@advanced_1364_td
#Security problem of certain encryption programs where the existence of certain data can be proven without decrypting. For more information, search in the internet for 'watermark attack cryptoloop'

@advanced_1365_td
SSL/TLS

@advanced_1366_td
#Secure Sockets Layer / Transport Layer Security. See also: <a href="http://java.sun.com/products/jsse/">Java Secure Socket Extension (JSSE)</a>

@advanced_1367_td
XTEA

@advanced_1368_td
#A block encryption algorithm. See also: <a href="http://en.wikipedia.org/wiki/XTEA">Wikipedia: XTEA</a>

@build_1000_h1
ビルド

@build_1001_a
# Portability

@build_1002_a
# Environment

@build_1003_a
# Building the Software

@build_1004_a
# Build Targets

@build_1005_a
# Using Maven 2

@build_1006_a
# Translating

@build_1007_a
# Providing Patches

@build_1008_a
# Reporting Problems or Requests

@build_1009_a
# Automated Build

@build_1010_a
# Generating Railroad Diagrams

@build_1011_h2
ポータビリティ

@build_1012_p
# This database is written in Java and therefore works on many platforms. It can also be compiled to a native executable using GCJ. 

@build_1013_p
# For Java 1.4, the jar file needs to be converted first using <a href="http://retrotranslator.sourceforge.net">Retrotranslator</a>. 

@build_1014_h2
環境

@build_1015_p
# A Java Runtime Environment (JRE) version 1.5 or higher is required to run this database. 

@build_1016_p
# To build the database executables, the following software stack was used. Newer version or compatible software works too. 

@build_1017_li
#Mac OS X and Windows XP 

@build_1018_a
#Sun JDK Version 1.5 and 1.6

@build_1019_a
#Eclipse Version 3.4

@build_1020_li
#Eclipse Plugins: <a href="http://subclipse.tigris.org">Subclipse 1.4.6</a>, <a href="http://eclipse-cs.sourceforge.net">Eclipse Checkstyle Plug-in 4.4.2</a>, <a href="http://www.eclemma.org">EclEmma Java Code Coverage 1.3.0</a> 

@build_1021_a
#Emma Java Code Coverage

@build_1022_a
#Mozilla Firefox 3.0

@build_1023_a
#OpenOffice 3.0

@build_1024_a
#NSIS 2.38

@build_1025_li
# (Nullsoft Scriptable Install System) 

@build_1026_a
#Maven 2.0.9

@build_1027_h2
ソフトウェアのビルド

@build_1028_p
# You need to install a JDK, for example the Sun JDK version 1.5 or 1.6. Ensure that Java binary directory is included in the <code>PATH</code> environment variable, and that the environment variable <code>JAVA_HOME</code> points to your Java installation. On the command line, go to the directory <code>h2</code> and execute the following command: 

@build_1029_p
# For Linux and OS X, use <code>./build.sh</code> instead of <code>build</code>. 

@build_1030_p
# You will get a list of targets. If you want to build the <code>jar</code> file, execute (Windows): 

@build_1031_h3
#Switching the Source Code

@build_1032_p
# By default the source code uses Java 1.5 features, however Java 1.6 is supported as well. To switch the source code to the installed version of Java, run: 

@build_1033_h2
#Build Targets

@build_1034_p
# The build system can generate smaller jar files as well. The following targets are currently supported: 

@build_1035_code
#jarClient

@build_1036_li
# creates the file <code>h2client.jar</code>. This only contains the JDBC client. 

@build_1037_code
#jarSmall

@build_1038_li
# creates the file <code>h2small.jar</code>. This only contains the embedded database. Debug information is disabled. 

@build_1039_code
#jarJaqu

@build_1040_li
# creates the file <code>h2jaqu.jar</code>. This only contains the JaQu (Java Query) implementation. All other jar files do not include JaQu. 

@build_1041_code
#javadocImpl

@build_1042_li
# creates the Javadocs of the implementation. 

@build_1043_p
# To create the file <code>h2client.jar</code>, go to the directory <code>h2</code> and execute the following command: 

@build_1044_h2
Maven 2 の利用

@build_1045_h3
Centralリポジトリの利用

@build_1046_p
# You can include the database in your Maven 2 project as a dependency. Example: 

@build_1047_p
# New versions of this database are first uploaded to http://hsql.sourceforge.net/m2-repo/ and then automatically synchronized with the main Maven repository; however after a new release it may take a few hours before they are available there. 

@build_1048_h3
スナップショットバージョンの利用

@build_1049_p
# To build a <code>h2-*-SNAPSHOT.jar</code> file and upload it the to the local Maven 2 repository, execute the following command: 

@build_1050_p
# Afterwards, you can include the database in your Maven 2 project as a dependency: 

@build_1051_h2
#Translating

@build_1052_p
# The translation of this software is split into the following parts: 

@build_1053_li
#H2 Console: <code>src/main/org/h2/server/web/res/_text_*.prop</code> 

@build_1054_li
#Error messages: <code>src/main/org/h2/res/_messages_*.prop</code> 

@build_1055_p
# To translate the H2 Console, start it and select Preferences / Translate. After you are done, send the translated <code>*.prop</code> file to the Google Group. The web site is currently translated using Google. 

@build_1056_h2
#Providing Patches

@build_1057_p
# If you like to provide patches, please consider the following guidelines to simplify merging them: 

@build_1058_li
#Only use Java 1.5 features (do not use Java 1.6) (see <a href="#environment">Environment</a>). 

@build_1059_li
#Follow the coding style used in the project, and use Checkstyle (see above) to verify. For example, do not use tabs (use spaces instead). The checkstyle configuration is in <code>src/installer/checkstyle.xml</code>. 

@build_1060_li
#A template of the Eclipse settings are in <code>src/installer/eclipse.settings/*</code>. If you want to use them, you need to copy them to the <code>.settings</code> directory. The formatting options (<code>eclipseCodeStyle</code>) are also included. 

@build_1061_li
#Please provide test cases and integrate them into the test suite. For Java level tests, see <code>src/test/org/h2/test/TestAll.java</code>. For SQL level tests, see <code>src/test/org/h2/test/test.in.txt</code> or <code>testSimple.in.txt</code>. 

@build_1062_li
#The test cases should cover at least 90% of the changed and new code; use a code coverage tool to verify that (see above). or use the build target <code>coverage</code>. 

@build_1063_li
#Verify that you did not break other features: run the test cases by executing <code>build test</code>. 

@build_1064_li
#Provide end user documentation if required (<code>src/docsrc/html/*</code>). 

@build_1065_li
#Document grammar changes in <code>src/docsrc/help/help.csv</code> 

@build_1066_li
#Provide a change log entry (<code>src/docsrc/html/changelog.html</code>). 

@build_1067_li
#Verify the spelling using <code>build spellcheck</code>. If required add the new words to <code>src/tools/org/h2/build/doc/dictionary.txt</code>. 

@build_1068_li
#Run <code>src/installer/buildRelease</code> to find and fix formatting errors. 

@build_1069_li
#Verify the formatting using <code>build docs</code> and <code>build javadoc</code>. 

@build_1070_li
#Submit patches as <code>.patch</code> files (compressed if big). To create a patch using Eclipse, use Team / Create Patch. 

@build_1071_p
# For legal reasons, patches need to be public in the form of an email to the <a href="http://groups.google.com/group/h2-database">group</a>, or in the form of an <a href="http://code.google.com/p/h2database/issues/list">issue report or attachment</a>. Significant contributions need to include the following statement: 

@build_1072_p
# "I wrote the code, it's mine, and I'm contributing it to H2 for distribution multiple-licensed under the H2 License, version 1.0, and under the Eclipse Public License, version 1.0 (http://h2database.com/html/license.html)." 

@build_1073_h2
#Reporting Problems or Requests

@build_1074_p
# Please consider the following checklist if you have a question, want to report a problem, or if you have a feature request: 

@build_1075_li
#Feature requests are always welcome, even if the feature is already on the <a href="roadmap.html">roadmap</a>. Your mail will help prioritize feature requests. If you urgently need a feature, consider <a href="#providing_patches">providing a patch</a>. 

@build_1076_li
#Before posting problems, check the <a href="faq.html">FAQ</a> and do a <a href="http://google.com">Google search</a>. 

@build_1077_li
#When got an unexpected exception, please try the <a href="sourceError.html">Error Analyzer tool</a>. If this doesn't help, please report the problem, including the complete error message and stack trace, and the root cause stack trace(s). 

@build_1078_li
#When sending source code, please use a public web clipboard such as <a href="http://pastebin.com">Pastebin</a>, <a href="http://cl1p.net">Cl1p</a>, or <a href="http://www.mysticpaste.com/new">Mystic Paste</a> to avoid formatting problems. Please keep test cases as simple and short as possible, but so that the problem can still be reproduced. As a template, use: <a href="http://h2database.googlecode.com/svn/trunk/h2/src/test/org/h2/samples/HelloWorld.java">HelloWorld.java</a>. Method that simply call other methods should be avoided, as well as unnecessary exception handling. Please use the JDBC API and no external tools or libraries. The test should include all required initialization code, and should be started with the main method. 

@build_1079_li
#For large attachments, use a public temporary storage such as <a href="http://rapidshare.com">Rapidshare</a>. 

@build_1080_li
#Google Group versus issue tracking: Use the <a href="http://groups.google.com/group/h2-database">Google Group</a> for questions or if you are not sure it's a bug. If you are sure it's a bug, you can create an <a href="http://code.google.com/p/h2database/issues/list">issue</a>, but you don't need to (sending an email to the group is enough). Please note that only few people monitor the issue tracking system. 

@build_1081_li
#For out-of-memory problems, please analyze the problem yourself first, for example using the command line option <code>-XX:+HeapDumpOnOutOfMemoryError</code> and a memory analysis tool such as the <a href="http://www.eclipse.org/mat">Eclipse Memory Analyzer (MAT)</a>. 

@build_1082_li
#It may take a few days to get an answers. Please do not double post. 

@build_1083_h2
#Automated Build

@build_1084_p
# This build process is automated and runs regularly. The build process includes running the tests and code coverage, using the command line <code>./build.sh clean jar coverage -Dh2.ftpPassword=... uploadBuild</code>. The last results are available here: 

@build_1085_a
#Test Output

@build_1086_a
#Code Coverage Summary

@build_1087_a
#Code Coverage Details (download, 1.3 MB)

@build_1088_a
#Build Newsfeed

@build_1089_a
#Latest Jar File (download, 1 MB)

@build_1090_h2
#Generating Railroad Diagrams

@build_1091_p
# The railroad diagrams are HTML, formatted as nested tables. The diagrams are generated as follows: 

@build_1092_li
#The BNF parser (<code>org.h2.bnf.Bnf</code>) reads and parses the BNF from the file <code>help.csv</code>. 

@build_1093_li
#The page parser (<code>org.h2.server.web.PageParser</code>) reads the template HTML file and fills in the diagrams. 

@build_1094_li
#The rail images (one straight, four junctions, two turns) are generated using a simple Java application. 

@build_1095_p
# To generate railroad diagrams for other grammars, see the package <code>org.h2.jcr</code>. This package is used to generate the SQL-2 railroad diagrams for the JCR 2.0 specification. 

@changelog_1000_h1
変更履歴

@changelog_1001_h2
#Next Version (unreleased)

@changelog_1002_li
#A new class org.h2.tools.TriggerAdapter allows to use the ResultSet interface within trigger implementations. 

@changelog_1003_li
#A subselect which used an index could lead to wrong results. Fixed. 

@changelog_1004_li
#Creating a cached temporary non persistent table with a primary key threw a NullPointerException. 

@changelog_1005_h2
#Version 1.2.135 (2010-05-08)

@changelog_1006_li
#Temporary files were not deleted when using large transactions, disabling autocommit, and closing the session without committing. 

@changelog_1007_li
#Queries using multiple IN(..) conditions on the same table could cause repeated rows in the result set. 

@changelog_1008_li
#Translation: Lubomir Grajciar translated the H2 Console as well as all error message to Slovensky. Thanks a lot! 

@changelog_1009_li
#There was a possible Java level deadlock when opening an uninitialized database and using a file system that also opened a database. 

@changelog_1010_li
#When killing the process while the database was writing a checkpoint, while it was closing, or while running recovery (while removing temporary tables from a previous run), the database could become corrupt. A new test case has been implemented to ensure such problems can not occur in the future. 

@changelog_1011_li
#File system: new method FileSystem.setReadOnly. 

@changelog_1012_li
#The page size for new databases can now be set in the database URL using ;PAGE_SIZE=512. Currently this feature is only used to simplify testing. 

@changelog_1013_li
#New system property h2.functionsInSchema (default is false). If enabled, the SCRIPT statement always includes the schema name in the CREATE ALIAS statement (even if the schema is PUBLIC). This is not backward compatible with H2 versions 1.2.134 and older. 

@changelog_1014_li
#Functions: it is no longer required to add a space after a comma in the parameter list. Example: CREATE ALIAS PARSE_INT FOR "java.lang.Integer.parseInt(java.lang.String,int)" 

@changelog_1015_li
#Functions now reside within a schema, similar to sequences. If you do create such functions in schemas other than PUBLIC, then the database can not be opened with older versions of H2. 

@changelog_1016_li
#Cluster: after a cluster node failed, the second cluster node can now be re-created and started without having to stop the first cluster node, and without having to stop running applications. To do that, append ;AUTO_RECONNECT=TRUE to the database URL. 

@changelog_1017_li
#Auto-reconnect: if another connection uses the database in exclusive mode then this connection will try to re-connect until the exclusive mode ends. This is important when using the cluster mode. 

@changelog_1018_li
#SET EXCLUSIVE now supports 0 (disable), 1 (enable), and 2 (enable and close all other connections). 

@changelog_1019_li
#Installing the H2 as a service should now work on Windows 7. The batch files now explicitly set the directory using pushd "%~dp0". 

@changelog_1020_li
#Temporary tables can now be 'cached', that means indexes of temporary tables can be persisted. This enables very large temporary tables (both local and global). 

@changelog_1021_li
#The CreateCluster tool now sets the source database in exclusive mode before copying data to the new database. 

@changelog_1022_li
#The H2 Console now stream results one statement / result set at a time (using chunked transfer encoding). To disable, set the system property h2.consoleStream to false. This feature is not supported when using a servlet container. 

@changelog_1023_li
#The H2 Console did not call the CreateCluster tool with the correctly escaped parameters. 

@changelog_1024_li
#Improved PostgreSQL compatibility for ALTER TABLE ALTER COLUMN. 

@changelog_1025_li
#Commas at the end of INSERT ... VALUES (), (), are now supported. 

@changelog_1026_li
#The H2 Console "Start Browser" button now works even when the IP address changes while the tool runs (for example, because a wireless connection breaks, or when enabling / disabling the network connection). 

@changelog_1027_li
#When casting from float or double to BigDecimal, the result was sometimes unexpected, because "new BigDecimal(double val)" was used. Now "BigDecimal.valueOf(double val)" and "new BigDecimal(Float.toString(f))" are used. But it is still not recommended to use float or double for currency values (see data type documentation). 

@changelog_1028_li
#Global temporary tables are now deleted when closing the database. Before, they were deleted when opening the database the next time. 

@changelog_1029_li
#UNIQUE was not listed as a keyword. 

@changelog_1030_li
#Improved error message when an non-SQL-exception occurred in a user defined function. The method name and parameters are included in the error message. 

@changelog_1031_li
#For some queries, the exception did not include the SQL statement. Example: select x from system_range(1, 2) group by 'a'. 

@changelog_1032_li
#The Shell tool will execute SQL statements passed as using the command line parameter -sql. 

@changelog_1033_li
#If InetAddress.getLocalHost() fails, the database should now throw an exception. 

@changelog_1034_li
#New columns INFORMATION_SCHEMA.INDEXES.INDEX_CLASS and INFORMATION_SCHEMA.TABLES.TABLE_CLASS. 

@changelog_1035_li
#INFORMATION_SCHEMA.INDEXES.SQL now contains the CREATE INDEX statement instead of just the fully qualified index name. 

@changelog_1036_h2
#Version 1.2.134 (2010-04-23)

@changelog_1037_li
#New system property h2.analyzeAuto (default 0 meaning disabled) to automatically run ANALYZE after that many changes to a table. For details, see the Javadoc of this system property. The plan is to set this property to 2000 in version 1.3.x. 

@changelog_1038_li
#JdbcXAConnection.start() does not support TMJOIN. Issue 189. 

@changelog_1039_li
#MySQL compatibility: TIMESTAMPDIFF is now an alias for DATEDIFF. 

@changelog_1040_li
#MERGE did not respect foreign key and check constraints. 

@changelog_1041_li
#ALTER TABLE ALTER COLUMN: changing the data type of a column no longer makes it nullable. 

@changelog_1042_li
#When using AUTO_SERVER=TRUE, the server is now started as a daemon thread. This was a problem when using Tomcat and a connection pool. 

@changelog_1043_li
#Servers can now be started as a daemon thread using the command line options -tcpDaemon, -pgDaemon, and -webDaemon. 

@changelog_1044_li
#H2 Console: the built-in commands are now documented. 

@changelog_1045_li
#REPLACE: if any parameter is null, the result is null. 

@changelog_1046_li
#Queries with DISTINCT and ORDER BY will now use the index on ORDER BY if possible. This is specially important for queries used inside IN(SELECT ...). 

@changelog_1047_li
#The new statement EXPLAIN ANALYZE executes the statement, and displays the query plan with the actual row scan count for each table. 

@changelog_1048_li
#H2 Console: the auto-complete feature didn't quote column names that need quoting. Issue 186. 

@changelog_1049_li
#The experimental LOB storage mechanism now supports all features of the old one. To use it, set the system property "h2.lobInDatabase" to "true". If you have used this feature in version 1.2.133, you need to export and re-import the database using SCRIPT / RUNSCRIPT. 

@changelog_1050_li
#The functions isBeforeFirst() and isAfterLast() were not compliant to the JDBC spec. If the ResultSet contains no rows, they must return false. Fixed. 

@changelog_1051_li
#Filesystem parameters like "split:" didn't work in server mode with baseDir set. 

@changelog_1052_li
#If baseDir is set, and a database name is given which points to a directory outside the baseDir (eg. "../dbname"), an exception is thrown. 

@changelog_1053_h2
#Version 1.2.133 (2010-04-10)

@changelog_1054_li
#A new experimental LOB storage mechanism is available. When enabled, CLOB and BLOB data is stored in hidden tables in the database. To use it, set the system property "h2.lobInDatabase" to "true". Compression is not yet implemented. Duplicate objects are only stored once. Usually writing is slower, but reading is faster (mainly because of caching). 

@changelog_1055_li
#The Shell tool threw a NumberFormatException on a empty statement. 

@changelog_1056_li
#The h2small-*.jar did not support "drop all objects delete files". Now it is supported (the DeleteDbFiles tool is now included). 

@changelog_1057_li
#Operations that don't fit in memory are now faster. Temporary file handling was changed. 

@changelog_1058_li
#The default maximum log stream size is now 2 MB. This is a good value according to some performance tests. 

@changelog_1059_li
#New system property "h2.syncMethod" to configure what method to call when closing the database, on checkpoint, and on CHECKPOINT SYNC. The default is "sync" which calls RandomAccessFile.getFD().sync(). 

@changelog_1060_li
#ROWNUM could not be used for pagination. The follow query returned no rows: select x from (select *, rownum as r from system_range(1, 3)) where r=2; 

@changelog_1061_li
#Workaround for a java.sql.Date issue: years above 9999 are not formatted correctly. When calling ResultSet.getString() on a date value, an alternative formatting algorithm is used. 

@changelog_1062_li
#Prepared statements with nested subqueries did not always return the correct result. Example: select ?, ?, (select count(*) from test t, (select id from test where 0=?) t2 where t2.id=t.id) from test 

@changelog_1063_li
#When using MULTI_THREADED=TRUE, the exception following exception could be thrown: "object already exists: TABLES" 

@changelog_1064_li
#Comparison of integer columns against float numbers was not always correct. Issue 182. 

@changelog_1065_li
#H2 Console: Editing the result of a multi-line queries failed. Issue 183. 

@changelog_1066_li
#H2 Console: if the settings file (.h2.properties) can't be accessed, the exception is now ignored. 

@changelog_1067_h2
#Version 1.2.132 (2010-03-21)

@changelog_1068_li
#The implementation of a Java to C (source code level) converter has been started. The plan is: it should be possible to convert H2 (or a part of it) to C so that the database can be run without a JVM. This will be a long term project (it may take a year or so). 

@changelog_1069_li
#User defined table implementation can now be used using CREATE TABLE ... ENGINE. Thanks to Sergi Vladykin for implementing this feature! 

@changelog_1070_li
#Improved MS SQL Server compatibility: support string concatenation using "+". Thanks to Stepan for the patch! 

@changelog_1071_li
#When using the multi-threaded mode, running ANALYZE concurrently in multiple connections could throw an exception. 

@changelog_1072_li
#The MERGE statement is now about 30% faster when using a PreparedStatement. 

@changelog_1073_li
#Multi-column indexes where the second or later column was descending did not always produce correct results (rows were missing in the result set, or the result set was empty). 

@changelog_1074_li
#When using large transactions or a small log size, the database could get very slow (profiling shows the hotspot is in FileObjectDisk.sync()). 

@changelog_1075_li
#The Shell tool now prints the stack trace when the list mode is enabled. 

@changelog_1076_li
#CREATE ALIAS ... AS: Compilation was incorrect if the source code contained characters that are not supported by the default file encoding. 

@changelog_1077_li
#Issue 176: the JdbcDataSource now also supports a 'description' property. 

@changelog_1078_li
#The Shell tool threw a ArrayIndexOutOfBoundsException after 20 statements. 

@changelog_1079_li
#When using the small version of H2 ('jarClient'), the first call to Connection.createBlob (or similar) could throw a ClassNotFoundException because the file org.h2.store.fs.FileSystemZip is not included. This missing class is now ignored. 

@changelog_1080_li
#Literals of type BIGINT now have the correct data type. 

@changelog_1081_h2
#Version 1.2.131 (2010-03-05)

@changelog_1082_li
#Older versions of H2 (version 1.2.127 and older) could not connect to a new version (version 1.2.129 and newer). The connection blocked when trying to connect. Now the connection no longer blocks, instead a SQL exception is thrown. 

@changelog_1083_li
#In versions 1.2.129 and 1.2.130, a database could not be opened sometimes after dropping tables or indexes, and then creating new indexes for existing tables. The exception contained the text "parent not found" (version 1.2.129) or "Table not found" (version 1.2.130). 

@changelog_1084_li
#After the database was closed, a null pointer exception could occur in Database.flush. 

@changelog_1085_li
#An ArrayIndexOutOfBoundsException could occur in the page store (eg. on "delete from table"). Fixed. 

@changelog_1086_h2
#Version 1.2.130 (2010-02-26)

@changelog_1087_li
#EXPLAIN: The query plan now contains ".tableScan" if a table scan is used. 

@changelog_1088_li
#IN(..): when combining and IN(..) condition with a condition that didn't use an index, the result could contain duplicate rows. 

@changelog_1089_li
#IN(..): the index was not used if there were multiple IN(..) conditions. 

@changelog_1090_li
#For foreign key constraints, the metadata column INFORMATION_SCHEMA.INDEXES.CONSTRAINT_NAME was not set for non-unique indexes. 

@changelog_1091_li
#PostgreSQL compatibility: when using the following exception was thrown: Column "T.TYPTYPMOD" not found. Fixed. This is only when using psqlodbc_08_04*. 

@changelog_1092_li
#A tool to migrate an old database from the non-page store format to the newest version has been added in src/tools/org/h2/dev/util/Migrate.java. This file is not included in the jar file currently. 

@changelog_1093_li
#When using temporary tables, the database didn't shrink sometimes when closing. Also, sometimes a database could not recover normally. 

@changelog_1094_li
#Large transactions could run out of heap space. The maximum size of a transaction is now much larger. 

@changelog_1095_li
#The default setting for the system property h2.webMaxValueLength is now 100000 (it was 10000 before). 

@changelog_1096_li
#Creating a database was delayed about 2 seconds if the directory didn't exist. 

@changelog_1097_li
#Implemented INIT feature. If the database URL contains ";INIT=...;" then the DDL or DML commands following are executed on startup. Example URL: jdbc:h2:mem:test;INIT=RUNSCRIPT FROM '~/create.sql' (patch from Kerry Sainsbury). 

@changelog_1098_h2
#Version 1.2.129 (2010-02-19)

@changelog_1099_li
#The methods of the CloseListener are added to the Trigger interface. The interface CloseListener is removed. This is potentially a breaking change for existing triggers. 

@changelog_1100_li
#CREATE ALIAS: error message when compiling Java code have been improved. 

@changelog_1101_li
#MVCC: creating a table with an incorrect constraint could cause strange errors. 

@changelog_1102_li
#Hash indexes now are only used for single column indexes. 

@changelog_1103_li
#The cache types WEAK_* and TQ are no longer supported. A weak reference cache never frees up memory so it's the same as having a very large cache size. The TQ cache was not included in the jar file since a longer time, and was not tested. 

@changelog_1104_li
#The file system abstraction no longer throws SQL exceptions. 

@changelog_1105_li
#DatabaseEventListener.diskSpaceIsLow has changed. 

@changelog_1106_li
#The CompressTool no longer throw as SQL exceptions. Instead, it throws runtime exceptions. 

@changelog_1107_li
#SimpleResultSet.addColumn and addRow now can throw a IllegalStateException instead of a SQLException. 

@changelog_1108_li
#When doing an index lookup, decimal values with the same value but different scale (for example 0.00 and 0.0) where not considered equal in version 1.2.128. Now they are (unlike BigDecimal.equals()). 

@changelog_1109_li
#The BNF parser now uses the visitor pattern. 

@changelog_1110_li
#Converting a UUID to bytes was incorrect. Because of that, updatable result sets on tables with UUID primary key did not work. 

@changelog_1111_li
#The database URL property DATABASE_EVENT_LISTENER_OBJECT is no longer supported (there are problems passing objects when the PostgreSQL driver is installed as well). 

@changelog_1112_li
#H2 Console: asynchronous login (using a DatabaseEventListener) is no longer supported. 

@changelog_1113_li
#A workaround for a Windows socket problem has been implemented. Thanks a lot to Sergi Vladykin. 

@changelog_1114_li
#The Recover tool did not convert correctly convert CLOB data with non-ASCII characters. 

@changelog_1115_li
#Tools: the method run(String... args) has been renamed to runTool(String... args). 

@changelog_1116_li
#Server.startWebServer(Connection) was not working as expected. 

@changelog_1117_li
#The database URL option ACCESS_MODE_LOG is no longer supported. 

@changelog_1118_li
#The database URL option RECOVER has currently no effect. 

@changelog_1119_li
#Converting an old (non-page store) database is no longer supported using this version. 

@changelog_1120_li
#The following system properties are no longer supported: h2.overflowExceptions, h2.optimizeDropDependencies, h2.optimizeGroupSorted, h2.optimizeMinMax, h2.optimizeNot, h2.optimizeIn, h2.optimizeInJoin, h2.reuseSpace*. Most of then were there for a long time, but always with the same value. There was no unit test with the other value. So changing them was potentially dangerous (not a lot, but still). 

@changelog_1121_li
#The setting LOG has currently no effect (it only had an effect when the page store was disabled). 

@changelog_1122_li
#Disabling the page store is no longer supported. The old storage mechanism has been removed, shrinking the jar file size by almost 10%. 

@changelog_1123_li
#The translated resources are now stored in UTF-8 format. 

@changelog_1124_li
#The Windows service wrapper now detects if multiple versions of H2 are installed. 

@changelog_1125_h2
#Version 1.2.128 (2010-01-30)

@changelog_1126_li
#There are known errors on rollback when the page store is disabled and at the same time MVCC is used. See http://code.google.com/p/h2database/issues/detail?id=158 

@changelog_1127_li
#The DeleteDbFiles tool deleted all files in the .lob.db directory, even files that didn't belong to the database. 

@changelog_1128_li
#Automatic conversion of old databases to the page store format failed if the database contained LOB files. 

@changelog_1129_li
#Nested subqueries didn't work for INSERT INTO and IN(..). Example: insert into test ((select 1)); 

@changelog_1130_li
#If the database was already closed using SHUTDOWN IMMEDIATELY, closing a second connection could throw a NullPointerException if there was a local temporary table. 

@changelog_1131_li
#Less classes are loaded when using the database in embedded mode. 

@changelog_1132_li
#The information schema tables are only initialized when needed. This reduces memory usage and speeds up creating in-memory databases. Each in-memory database needs about 8 KB of heap memory. 

@changelog_1133_li
#Nested UNION/INTERSECT queries with brackets could produce the wrong result if used within a subquery. Example: select count(*) from (select 1 union (select 2 intersect select 2)) x; 

@changelog_1134_li
#Comparing an column against a constant expression with a higher precision or length than the column could give wrong results (the expression was truncated before comparing). 

@changelog_1135_li
#Improved PostgreSQL compatibility (support SHOW DEFAULT_TRANSACTION_ISOLATION). 

@changelog_1136_li
#Documentation: the javadocs for Csv.write and read used the wrong default charset. 

@changelog_1137_li
#MVCC: if the table was locked in exclusive mode (such as SELECT ... FOR UPDATE), another session could query the table. This is now longer possible. 

@changelog_1138_li
#If a FOR UPDATE query was executed twice (using a PreparedStatement), the table was not locked. 

@changelog_1139_li
#Triggers: INSTEAD OF triggers are now supported. Such triggers can be defined on views. 

@changelog_1140_li
#New system property h2.identifiersToUpper. If set to false, identifiers in SQL statements are case sensitive even if they are not quoted. 

@changelog_1141_li
#Slightly improved performance if the table is already locked. 

@changelog_1142_li
#CompressLZF: faster decompression. 

@changelog_1143_li
#PgServer: the wrong size was sent for VARCHAR data. Thanks again to Sergi Vladykin for the patch. 

@changelog_1144_li
#Serialized access mode (server-less multi-connection mode): fixed getGeneratedKeys() for sequences. 

@changelog_1145_h2
#Version 1.2.127 (2010-01-15)

@changelog_1146_li
#Serialized access mode (server-less multi-connection mode): sequences did not work as expected (there were gaps in generated values when using multiple connections). 

@changelog_1147_li
#Page store: new databases can not be opened with older versions. 

@changelog_1148_li
#Page store: adding data to new database is now faster. 

@changelog_1149_li
#File system: getting the file name from a path is now faster. This should speed up BLOB and CLOB access. 

@changelog_1150_li
#PgServer: incorrect SQL types were returned in result set meta data. Concurrently opening a database could fail (PG catalog initialization was not synchronized). Thanks a lot to Sergi Vladykin for providing the patches! 

@changelog_1151_li
#SHOW COLUMNS did not work correctly if there where multiple indexes on the same columns. 

@changelog_1152_li
#Page store: the wrong write count was written to the database header. This could cause the server-less multi-connection mode to fail. 

@changelog_1153_li
#Result sets larger than 2 GB threw an exception "Negative seek offset". Fixed. 

@changelog_1154_li
#If the system property h2.check was set to false, an ArrayIndexOutOfBoundsException could occur. 

@changelog_1155_li
#Alter table is now supported even if a table has views defined. 

@changelog_1156_li
#Fulltext search: exceptions within the fulltext search package had the wrong SQL state. 

@changelog_1157_li
#The Lucene fulltext search ignored transaction rollback. Fixed using a trigger on rollback. 

@changelog_1158_li
#Trigger can now be called on rollback. 

@changelog_1159_li
#The shell script h2.sh ignored command line line arguments. 

@changelog_1160_li
#When running H2 in the Google AppEngine for Java, a AccessControlException could be thrown when trying to open a read-only database. Fixed. 

@changelog_1161_li
#The user home directory prefix (~) is now only expanded when followed by a slash or backslash, or standing alone. 

@changelog_1162_li
#Native fulltext search: before inserting or deleting data, FT_INIT() had to be called. This is no longer required. 

@changelog_1163_li
#The .trace.db file is now only created if required. 

@changelog_1164_li
#Shell tool: improved PostgreSQL compatibility. 

@changelog_1165_li
#Trying to open a database in read-only mode when a .lock.db file exists will now fail with a nice error message. 

@changelog_1166_li
#H2 Console: data that is too long is now abbreviated as follows: text... (100000 characters). A large binary is abbreviated as follows: abcdef... (100000 bytes). 

@changelog_1167_li
#Faster data conversion from BIGINT or INT to DECIMAL. 

@changelog_1168_li
#Server-less multi-connection mode: try to delete log files if switching between read/write operations. 

@changelog_1169_li
#CompressLZF: Faster decompress and improved javadocs 

@changelog_1170_h2
#Version 1.2.126 (2009-12-18)

@changelog_1171_li
#The ChangeFileEncryption tool will now fail with an exception if the database is still in use. The Backup tool will also fail except when running in quiet mode. 

@changelog_1172_li
#CSVREAD: when reading the column names from the CSV file, column names that contain no special characters are considered case insensitive now. 

@changelog_1173_li
#Optimization index conditions of the form 'column=NULL' (which is always false; unlike 'column IS NULL'). 

@changelog_1174_li
#Script command and tool: the primary key constraint is now listed before inserting the data. This will result in a smaller database when using the page store. 

@changelog_1175_li
#Statements with IN(SELECT..) conditions could produce the wrong result. Example: index on id, name; query: select * from test where id between 1 and 3 and name in (select 'World'). 

@changelog_1176_li
#Statements with IN(..) conditions could produce the wrong result when using views or nested select statements. Example: index on id; index on name; query: select * from (select * from test) where id=1 and name in('a', 'b'). select * from (select * from test) where id=1 and name in('Hello', 'World'). 

@changelog_1177_li
#Page store: a rollback of a relatively large transaction could fail with an ArrayIndexOutOfBoundsException or a 'row not found' exception in the PageBtreeIndex in some cases. 

@changelog_1178_li
#JaQu: the decompiler has been improved, and a few test cases already work. It is still incomplete however. 

@changelog_1179_li
#LIKE: any letter is now allowed after the escape character (which is still '\' by default). Previously, an exception was thrown (unlike other databases) if it was not the escape character, '_' or '%'. If the escape character appears at the end of the pattern, the result is it is ignored (like PostgreSQL and MS SQL Server). 

@changelog_1180_li
#The reserve heap memory is no longer used. 

@changelog_1181_li
#Database.checkpoint() could throw a NullPointerException. 

@changelog_1182_h2
#Version 1.2.125 (2009-12-06)

@changelog_1183_li
#Lucene fulltext search: the Lucene field names now match the table column names, except if the column names start with _ (in which case another _ is prepended). Unfortunately this change means existing fulltext indexes need to be re-built. 

@changelog_1184_li
#The shell tool now has a very simple statement history. 

@changelog_1185_li
#The zip file system implementation now supports the '~' home directory prefix. Example database URL: jdbc:h2:zip:~/test.zip!/test 

@changelog_1186_li
#Right outer joins on tables that were already 'inner joined' was processed incorrectly. 

@changelog_1187_li
#Temporary files from LOB objects were not deleted early enough when using the server mode. 

@changelog_1188_li
#Trying to alter a temporary table threw a strange exception. It is still not possible to do that, but the exception message is better now. 

@changelog_1189_li
#When the system property h2.maxMemoryRowsDistinct was set, and using SELECT DISTINCT, the temporary table was not correctly dropped. This could cause problems in recovery when the process was killed. 

@changelog_1190_li
#Trigger that are called before a select statement are now supported. This allows to create tables that work like materialized views. 

@changelog_1191_li
#Non-row based triggers were called even if the action didn't match the declared action (INSERT triggers were also called when deleting rows). This has been changed. The MERGE statement calls both INSERT and DELETE triggers. 

@changelog_1192_li
#Statements with IN(..) conditions could produce the wrong result or a data conversion error (since version 1.2.120). Examples: index on id, name, condition: id=1 and name in('Hello', 'x'); index on id, query: select * from (select * from test) where id=1 and name in('Hello', 'World'). 

@changelog_1193_li
#The CompressTool was not multithreading safe. Because of this, the following database operations where also not multithreading safe (even when using different databases): the SCRIPT command (only when using compression), the COMPRESS function, and storing CLOB or BLOB data (only when compression is enabled). 

@changelog_1194_li
#The compression algorithm "LZF" is now about 33% faster than before when compressing small block (around 2 KB). It is much faster than Deflate, but the compression ratio is lower. Some of the optimizations are from Sam Van Oort, thanks a lot! 

@changelog_1195_li
#Compressing large blocks of data didn't work when using the "Deflate" compression algorithm. Compressing a lot of data could run out of heap memory. 

@changelog_1196_li
#The test cases don't access the file system directly, this simplifies GAE for Java testing. Thanks to Vince Bonfanti. 

@changelog_1197_li
#More bugs in the server-less multi-connection mode have been fixed. 

@changelog_1198_li
#When running against an old database, the SCRIPT statement could generate a SQL script that contained duplicate indexes (PRIMARY_KEY_E). 

@changelog_1199_li
#JdbcConnectionPool.getConnection() could throw a NullPointerException. 

@changelog_1200_li
#User defined functions: the source code is now available using SELECT SOURCE FROM INFORMATION_SCHEMA.FUNCTION_ALIASES. 

@changelog_1201_li
#User defined functions with source code didn't work after re-opening the database. 

@changelog_1202_li
#The newsfeeds are now Atom 1.0 standard compliant. 

@changelog_1203_li
#The database is now closed after an out of memory exception, because the database could get corrupt otherwise. 

@changelog_1204_li
#Better error message if both AUTO_SERVER and SERIALIZED parameters are set to TRUE. 

@changelog_1205_li
#Drop table did not delete lob files in old file store (not PAGE_STORE). 

@changelog_1206_h2
#Version 1.2.124 (2009-11-20)

@changelog_1207_li
#Clustering: there is now a way to detect which cluster instances are running. 

@changelog_1208_li
#ConvertTraceFile: the SQL statement statistics are better formatted (newline are removed). 

@changelog_1209_li
#The file lock thread is now stopped when the database is closed. 

@changelog_1210_li
#Issue 140: the Script tool now supports writing to a stream. 

@changelog_1211_li
#Issue 138: the trace output of Statement.execute(String, int) and executeUpdate was incorrect. 

@changelog_1212_li
#Page store: new databases can not be opened with older versions. 

@changelog_1213_li
#Page store: multi-column indexes didn't work if the cache was very small. 

@changelog_1214_li
#Page store: opening a database could theoretically result in an endless loop. 

@changelog_1215_li
#Page store: adding large indexed columns could get very slow. 

@changelog_1216_li
#Page store: after a duplicate key exception, an ArrayIndexOutOfBoundsException could be thrown (only for very large rows). 

@changelog_1217_li
#Page store: the recover tool sometimes generated a script file that contained duplicate data. 

@changelog_1218_li
#Page store: sometimes opening a read-only database failed. 

@changelog_1219_li
#Page store: opening a database sometimes failed if large rows where updated, or if a table was truncated before. 

@changelog_1220_li
#Page store: when using a very small page size (128 bytes or smaller), writing a large row could result in an endless recursion. This is only a theoretical problem, as the page size is 2 KB. 

@changelog_1221_li
#Page store: getting the min value from a descending index with NULL entries could return the wrong result. 

@changelog_1222_li
#Page store: improved auto-recovery after power failure. 

@changelog_1223_li
#The JDBC client did not detect that it was not talking to an H2 server. This could result in strange exceptions when trying to connect to another kind of server. 

@changelog_1224_li
#User defined functions can be created with source code. Example: CREATE ALIAS HI AS 'String hi() { return "Hello"; }' 

@changelog_1225_li
#Database file lock: the exception "lock file modified in the future" is no longer thrown; instead, opening the file will be delayed by 2 seconds. 

@changelog_1226_li
#Inserting LOBs got slower each time the process was restarted. It could loop endlessly after about 1000 process restarts. 

@changelog_1227_li
#Issue 117: Multi-version concurrency: concurrent MERGE statements now work. 

@changelog_1228_li
#Improved read-only database detection. 

@changelog_1229_h2
#Version 1.2.123 (2009-11-08)

@changelog_1230_li
#Page store: new databases can not be opened with older versions. 

@changelog_1231_li
#Page store: updating large rows (rows with more than 2000 bytes of data) could corrupt the database. 

@changelog_1232_li
#Page store: inserting very large rows failed with ArrayIndexOutOfBoundsException. 

@changelog_1233_li
#When using multi-threaded kernel mode, setting disabling locking (LOCK_MODE=0) will now throw an exception. At this time this combination will result in corruption when multiple threads try to update the same table. 

@changelog_1234_li
#The fulltext search methods and fields are now protected instead of private, to make the classes more easily extensible. 

@changelog_1235_li
#The Lucene fulltext search now also returns the score. 

@changelog_1236_li
# New function SCOPE_IDENTITY() to avoid problems when inserting rows in a trigger. 

@changelog_1237_li
#Statement.getGeneratedKeys() returned the wrong value if a trigger changed the identity value after inserting the row. 

@changelog_1238_li
#Improved error messages: identifiers and values are now quoted. 

@changelog_1239_li
#Improved error message when casting a value failed: the column name and type is included in the message. 

@changelog_1240_li
#Improved support for GAE for Java thanks to Vince Bonfanti. 

@changelog_1241_h2
#Version 1.2.122 (2009-10-28)

@changelog_1242_li
#The native fulltext search now supports streaming CLOB data. 

@changelog_1243_li
#If the database URL ends with ;PAGE_STORE=TRUE and a database in the old format exists, it is automatically converted to the new page store format if possible. A backup of the database is created first. Automatic conversion is not supported if the database was not closed normally (if it contains uncommitted transactions). 

@changelog_1244_li
#Dropping the current user is now allowed if another admin user exists. 

@changelog_1245_li
#Values of type BINARY or BLOB could not be converted to the data type OTHER. 

@changelog_1246_li
#SHUTDOWN COMPACT now fully compacts the database. 

@changelog_1247_li
#New system properties h2.maxCompactCount and h2.maxCompactTime to allow changing the default behavior (at most 2 seconds compacting when closing the database). 

@changelog_1248_li
#New sorted insert optimization (see Performance / Database Performance Tuning). 

@changelog_1249_li
#Issue 116: The files h2*-sources.jar and h2*-javadoc.jar are now in the Maven repository. 

@changelog_1250_li
#Page store: opening a large database was slow if it was not closed before. 

@changelog_1251_li
#Page store: new write and read counters in the meta data table. Use SELECT * FROM INFORMATION_SCHEMA.SETTINGS WHERE NAME IN( 'info.FILE_WRITE_TOTAL', 'info.FILE_WRITE', 'info.FILE_READ', 'info.CACHE_MAX_SIZE', 'info.CACHE_SIZE') 

@changelog_1252_li
#The SQL syntax is documented using (railroad) diagrams. The diagrams are HTML. 

@changelog_1253_li
#The documentation is no longer available in Japanese because the translation was too much out of sync. Please use the Google translation instead. 

@changelog_1254_li
#Certain queries were not sorted if subselect queries were involved 

@changelog_1255_li
#More bugs in the server-less multi-connection mode have been fixed: 90097 The database is read only, caches must be cleared on reconnect, etc. 

@changelog_1256_h2
#Version 1.2.121 (2009-10-11)

@changelog_1257_li
#Better support GaeVFS (Google App Engine Virtual File System) thanks to Thanks to Vince Bonfanti. 

@changelog_1258_li
#CSVREAD didn't close the file. Thanks to Vince Bonfanti for the patch! 

@changelog_1259_li
#If a database in the old format exists, it is now used. The system property is used for new databases, or if databases exist in both formats. In any case, the flag in the URL overrides this logic. 

@changelog_1260_li
#Page store bugs were fixed. Large values in indexed columns could corrupt the index. 

@changelog_1261_li
#The page store did not work when using Retrotranslator (because the Retrotranslator doesn't support Integer.reverse and Long.reverse). 

@changelog_1262_li
#New system property h2.pageStoreTrim to disable shrinking the database when closing (disabled by default, meaning by default the database is trimmed). 

@changelog_1263_h2
#Version 1.2.120 (2009-10-04)

@changelog_1264_li
#This is a beta version. 

@changelog_1265_li
#Large updates could throw an ArrayIndexOutOfBoundsException in RowList.writeRow. 

@changelog_1266_li
#In version 1.2, the following system properties are now enabled by default: h2.pageStore, h2.nullConcatIsNull, h2.optimizeInList. The default value for h2.defaultMaxLengthInplaceLob is now 4096 (it was 1024 with version 1.1). 

@changelog_1267_li
#New databases are now stored in the new 'page store' file format. Existing databases are kept in the old file format. To use the old file format, append ;PAGE_STORE=FALSE to the database URL or set the system property h2.pageStore to false. 

@changelog_1268_li
#Issue 125: Renaming primary keys was not persistent. Fixed. Unfortunately, databases created by this version can not be opened with older versions because of this change. 

@changelog_1269_li
#Issue 124: Hibernate schema validation failed for decimal/numeric columns. This problem is fixed in the Hibernate dialect that is included with H2 (src/tools/org/hibernate/dialect/H2Dialect.java.txt), but not in Hibernate yet. 

@changelog_1270_li
#PostgreSQL compatibility: function LASTVAL() as an alias for IDENTITY(). 

@changelog_1271_li
#Linked tables now support default values when inserting, updating or merging. 

@changelog_1272_li
#Bugfixes in the page store. 

@changelog_1273_li
#Possibility to set a vendor id in Constants.java, so that unofficial builds are distinguishable from official releases. 

@changelog_1274_li
#Allow writing to linked tables in readonly databases. 

@changelog_1275_h2
#Version 1.1.119 (2009-09-26)

@changelog_1276_li
#SQL statements in the exception message are no longer included if they contain '--hide--'. 

@changelog_1277_li
#Temporary local tables did not always work after reconnect if AUTO_SERVER=TRUE 

@changelog_1278_li
#New system property h2.defaultMaxLengthInplaceLob to change the default maximum size of an in-place LOB object. 

@changelog_1279_li
#New system property h2.nullConcatIsNull to change the default null concatenation behavior. The default will be enabled in version 1.2. 

@changelog_1280_li
#The cache algorithm TQ is disabled in this version, because it is unstable, and because the current implementation does not have any measurable advantages over the default. 

@changelog_1281_li
#New committer: Christian Peter. He works for <a href="http://www.docware.com">Docware</a> and helped a lot finding and fixing bugs, and generally improving the database. He is now a committer. 

@changelog_1282_li
#ChangeFileEncryption did not work with Lob subdirectories. Fixed. 

@changelog_1283_li
#Issue 121: JaQu: new simple update and merge methods. 

@changelog_1284_li
#Issue 120: JaQu didn't close result sets. 

@changelog_1285_li
#Issue 119: JaQu creates wrong WHERE conditions on some inputs. 

@changelog_1286_li
#The new page store mechanism is now alpha-level quality. The next release will most likely be "1.2.120 beta" where this mode is enabled by default. To use it right now, append ;PAGE_STORE=TRUE to the database URL. The file format of this mode will probably not change any more. 

@changelog_1287_li
#SELECT COUNT(*) FROM SYSTEM_RANGE(...) returned the wrong result. Fixed. 

@changelog_1288_li
#The Recover tool now also processes the log files, however applying those changes is still a manual process. 

@changelog_1289_li
#New sample application that shows how to pass data to a trigger. 

@changelog_1290_li
#More bugs in the server-less multi-connection mode have been fixed: On Windows, two processes could write to the same database at the same time. 

@changelog_1291_li
#When loading triggers or other client classes (static functions, database event listener, user aggregate functions, other JDBC drivers), the database now uses the context class loader if the class could not be found using Class.forName(). 

@changelog_1292_li
#Updating many rows with the same CLOB or BLOB values could result in FileNotFoundException. 

@changelog_1293_li
#Statement.getConnection() threw an exception if the connection was already closed. 

@changelog_1294_li
#The native fulltext index kept a reference to a database after the database was closed. 

@changelog_1295_li
#Non-unique in-memory hash indexes are now supported. Thanks a lot to Sergi Vladykin for the patch! 

@changelog_1296_li
#The optimizer does a better job for joins if indexes are missing. 

@changelog_1297_h2
#Version 1.1.118 (2009-09-04)

@changelog_1298_li
#SHOW COLUMNS only listed indexed columns. 

@changelog_1299_li
#When calling SHUTDOWN IMMEDIATELY in the server mode, the .trace.db file was not closed. 

@changelog_1300_li
#DatabaseMetaData.getPrimaryKeys: the wrong constraint name was reported if there was another constraint on the same table and columns. 

@changelog_1301_li
#AUTO_INCREMENT now works in the same way in ALTER TABLE ALTER COLUMN as in CREATE TABLE (it does not create a primary key). 

@changelog_1302_li
#Native fulltext search: before searching, FT_INIT() had to be called. This is no longer required. 

@changelog_1303_li
#Better support GaeVFS (Google App Engine Virtual File System). 

@changelog_1304_li
#JaQu: the plan is to support natural (pure Java / Scala) conditions such as (id == 1 &amp;&amp; name.equals("Test")). A proof of concept decompiler is now included (it doesn't work yet). 

@changelog_1305_li
#Various bugfixes and improvements in the page store mechanism (still experimental). 

@changelog_1306_li
#PreparedStatement.setObject now converts a java.lang.Character to a string. 

@changelog_1307_li
#H2 Console: PierPaolo Ucchino has completed the Italian translation. Thanks a lot! 

@changelog_1308_li
#Various tools now use Java 5 var-args, such as main the methods and SimpleResultSet.addRow. 

@changelog_1309_li
#H2 Console: indexes of tables of non-default schemas are now also listed. 

@changelog_1310_li
#Issue 111: Multi-version concurrency / duplicate primary key after rollback. 

@changelog_1311_li
#Issue 110: Multi-version concurrency / wrong exception is thrown. 

@changelog_1312_li
#Parser: sequenceName.NEXTVAL and CURRVAL did not respect the schema search path. 

@changelog_1313_li
#Issue 101: The following sequence could throw the exception "Row not found when trying to delete": start a transaction, insert many rows, delete many rows, rollback. The number of rows depends on the cache size. 

@changelog_1314_li
#The stack trace of very common exceptions is no longer written to the .trace.db file by default. 

@changelog_1315_li
#An optimization for OR is implemented, but disabled by default. Expressions of the type X=1 OR X=2 are converted to X IN(1, 2). To enable, set the system property h2.optimizeInList to true before loading the H2 JDBC driver. 

@changelog_1316_li
#An optimization for IN(..) and IN(SELECT...) is implemented, but disabled by default. To enable, set the system property h2.optimizeInList to true before loading the H2 JDBC driver. If enabled, this overrides h2.optimizeIn and h2.optimizeInJoin. Unlike now, this optimization will also speed up updates and deletes. 

@changelog_1317_h2
#Version 1.1.117 (2009-08-09)

@changelog_1318_li
#New committer: Sam Van Oort has been contributing to H2 since quite some time in many ways (on the mailing list, documentation, and in the form of patches). He is now a committer. 

@changelog_1319_li
#JaQu: the order of the fields in the database no longer needs to match the order in the database. 

@changelog_1320_li
#Issue 103: MVCC: the setting MAX_MEMORY_UNDO can currently not be supported when using multi-version concurrency, that means the complete undo log must fit in memory. 

@changelog_1321_li
#LIKE: the escape mechanism can now be disable using ESCAPE ''. The default escape character can be changed using the system property h2.defaultEscape. The default is still '\' (as in MySQL and PostgreSQL). 

@changelog_1322_li
#Views using functions were not re-evaluated when necessary. 

@changelog_1323_li
#Improved MySQL compatibility for SHOW COLUMNS. 

@changelog_1324_li
#Improved PostgreSQL compatibility for timestamp literals with timezone. 

@changelog_1325_li
#Sergi Vladykin translated the error messages to Russian. Thanks a lot! 

@changelog_1326_li
#Support for Java 6 DatabaseMetaData.getTables, getColumns, getProcedures, and getProcedureColumns. 

@changelog_1327_li
#Issue 101: Rollback of a large transaction (more than 100000 rows) could fail. 

@changelog_1328_li
#Various bugfixes and improvements in the page store mechanism (still experimental). 

@changelog_1329_li
#The functions LENGTH, OCTET_LENGTH, and BIT_LENGTH now return BIGINT. 

@changelog_1330_li
#Data types CLOB and BLOB: the maximum precision was Integer.MAX_VALUE, it is now Long.MAX_VALUE. 

@changelog_1331_li
#Multi-threaded kernel: creating and dropping temporary database objects and the potentially free pages list was not correctly synchronized. Thanks a lot to Eric Faulhaber for the test case and patch! 

@changelog_1332_li
#Parsing SQL script files is now faster. 

@changelog_1333_li
#CSV reading is now faster. 

@changelog_1334_li
#SimpleResultSet.newInstance(SimpleRowSource rs) did not work. 

@changelog_1335_h2
#Version 1.1.116 (2009-07-18)

@changelog_1336_li
#Server-less multi-connection mode: more bugs are fixed. 

@changelog_1337_li
#The built-in help (INFORMATION_SCHEMA.HELP) is smaller, shrinking the jar file size a bit. 

@changelog_1338_li
#H2 Console: column of tables of non-default schemas are now also listed, except for schemas starting with 'INFO'. 

@changelog_1339_li
#ALTER TABLE: removing an auto-increment or identity column didn't remove the sequence. 

@changelog_1340_li
#Creating indexes is now a bit faster. 

@changelog_1341_li
#PG Server: new system property h2.pgClientEncoding to explicitly set the encoding for clients that don't send the encoding (the default encoding is UTF-8). Thanks a lot to Sergi Vladykin for the patch! 

@changelog_1342_li
#PG Server: improved compatibility by using the type ids of the PostgreSQL driver. Thanks a lot to Sergi Vladykin for the patch! 

@changelog_1343_li
#H2 Console: Oracle system tables are no longer listed, improving performance. 

@changelog_1344_li
#Result sets are now read-only except if the statement or prepared statement was created with the concurrency ResultSet.CONCUR_UPDATABLE. This change is required because the old behavior (all result set are updatable) violated the JDBC spec. For backward compatibility, use the system property h2.defaultResultSetConcurrency. 

@changelog_1345_li
#New system property h2.defaultResultSetConcurrency to change the default result set concurrency. 

@changelog_1346_li
#JDBC: using an invalid result set type or concurrency now throws an exception. 

@changelog_1347_li
#If a pooled connection was not closed but garbage collected, a NullPointerException could occur. 

@changelog_1348_li
#Fulltext search: a NullPointerException was thrown when updating a value that was NULL previously. 

@changelog_1349_li
#The Recover tool did not work with .data.db files of the wrong size. 

@changelog_1350_li
#Triggers: if there was an exception when initializing a trigger, this exception could be hidden, and in some cases (specially when using the Lucene fulltext index mechanism) a NullPointerException was thrown later on. Now the exception that occurred on init is thrown when changing data. 

@changelog_1351_li
#The soft-references cache (CACHE_TYPE=SOFT_LRU) could throw a NullPointerException. 

@changelog_1352_li
#To enable the new page store mechanism, append ;PAGE_STORE=TRUE to the database URL. or set the system property h2.pageStore to true. This mechanism is still experimental, and the file format will change, but it is quite stable now. 

@changelog_1353_h2
#Version 1.1.115 (2009-06-21)

@changelog_1354_li
#The new storage mechanism is now alpha quality. To try it out, set the system property "h2.pageStore" to "true" (java -Dh2.pageStore=true). There are still bugs to be found and fixed, for example inserting many rows references a lot of main memory. Performance is currently about the same as with the regular storage mechanism, but the database file size is smaller. The file format is not stable yet. 

@changelog_1355_li
#ALTER TABLE could throw an exception "object already exists" in some cases. 

@changelog_1356_li
#Views: in some situations, an ArrayIndexOutOfBoundsException was thrown when using the same view concurrently. 

@changelog_1357_li
#java.util.UUID is now supported in PreparedStatement.setObject and user defined Java functions. ResultSet.getObject() returns a java.util.UUID when using the UUID data type. 

@changelog_1358_li
#H2 Console: the language was reset to the browser language when disconnecting. 

@changelog_1359_li
#H2 Console: improved Polish translation. 

@changelog_1360_li
#Server-less multi-connection mode: more bugs are fixed. 

@changelog_1361_li
#The download page now included the SHA1 checksums. 

@changelog_1362_li
#Shell tool: the file encoding workaround is now documented if you run java org.h2.tools.Shell -?. 

@changelog_1363_li
#The RunScript tool and SQL statement did not work with the compression method LZF. 

@changelog_1364_li
#Fulltext search: searching for NULL or an empty string threw an exception. 

@changelog_1365_li
#Lucene fulltext search: FTL_DROP_ALL did not drop the triggers. 

@changelog_1366_li
#Backup: if the database contained CLOB or BLOB data, the backup included a file entry for the LOB directory. This caused the restore to fail. 

@changelog_1367_li
#Data types: LONG is now an alias for BIGINT. 

@changelog_1368_h2
#Version 1.1.114 (2009-06-01)

@changelog_1369_li
#ResultSetMetaData.getColumnClassName returned the wrong class for CLOB and BLOB columns. 

@changelog_1370_li
#Fulltext search: data is no longer deleted and re-inserted if the indexed columns didn't change. 

@changelog_1371_li
#In some situations, an ArrayIndexOutOfBoundsException was thrown when adding rows. This was caused by a bug in the b-tree code. 

@changelog_1372_li
#Microsoft Windows Vista: when using the the installer, Vista wrote "This program may not have installed correctly." This message should no longer appear (in the h2.nsi file, the line 'RequestExecutionLevel highest' was added). 

@changelog_1373_li
#The Recover tool did not always work when the database contains referential integrity constraints. 

@changelog_1374_li
#Java 1.5 is now required to run H2. If required, Retrotranslator can be used to create a Java 1.4 version (http://retrotranslator.sourceforge.net/). 

@cheatSheet_1000_h1
#H2 Database Engine Cheat Sheet

@cheatSheet_1001_h2
#Using H2

@cheatSheet_1002_a
H2

@cheatSheet_1003_li
# is <a href="http://code.google.com/p/h2database/source">open source</a>, <a href="license.html">free to use and distribute</a>. 

@cheatSheet_1004_a
ダウンロード

@cheatSheet_1005_li
#: <a href="http://repo1.maven.org/maven2/com/h2database/h2/1.2.135/h2-1.2.135.jar" class="link">jar</a>, <a href="http://www.h2database.com/h2-setup-2010-05-08.exe" class="link">installer (Windows)</a>, <a href="http://www.h2database.com/h2-2010-05-08.zip" class="link">zip</a>. 

@cheatSheet_1006_li
#To start the <a href="quickstart.html#h2_console">H2 Console tool</a>, double click the jar file, or run <code>java -jar h2*.jar</code>, <code>h2.bat</code>, or <code>h2.sh</code>. 

@cheatSheet_1007_a
#A new database is automatically created

@cheatSheet_1008_a
#by default

@cheatSheet_1009_li
#. 

@cheatSheet_1010_a
#Closing the last connection closes the database

@cheatSheet_1011_li
#. 

@cheatSheet_1012_h2
ドキュメント

@cheatSheet_1013_p
# Reference: <a href="grammar.html" class="link">SQL grammar</a>, <a href="functions.html" class="link">functions</a>, <a href="datatypes.html" class="link">data types</a>, <a href="tutorial.html#command_line_tools" class="link">tools</a>, <a href="../javadoc/index.html" class="link">API</a> 

@cheatSheet_1014_a
特徴

@cheatSheet_1015_p
#: <a href="tutorial.html#fulltext" class="link">fulltext search</a>, <a href="features.html#file_encryption" class="link">encryption</a>, <a href="features.html#read_only" class="link">read-only</a> <a href="features.html#database_in_zip" class="link">(zip/jar)</a>, <a href="tutorial.html#csv" class="link">CSV</a>, <a href="features.html#auto_reconnect" class="link">auto-reconnect</a>, <a href="features.html#triggers" class="link">triggers</a>, <a href="features.html#user_defined_functions" class="link">user functions</a> 

@cheatSheet_1016_a
#Database URLs

@cheatSheet_1017_a
#Embedded

@cheatSheet_1018_code
jdbc:h2:~/test

@cheatSheet_1019_p
# 'test' in the user home directory

@cheatSheet_1020_code
#jdbc:h2:/data/test

@cheatSheet_1021_p
# 'test' in the directory /data

@cheatSheet_1022_code
#jdbc:h2:test

@cheatSheet_1023_p
# in the current(!) working directory

@cheatSheet_1024_a
#In-Memory

@cheatSheet_1025_code
#jdbc:h2:mem:test

@cheatSheet_1026_p
# multiple connections in one process

@cheatSheet_1027_code
jdbc:h2:mem:

@cheatSheet_1028_p
# unnamed private; one connection

@cheatSheet_1029_a
サーバーモード

@cheatSheet_1030_code
#jdbc:h2:tcp://localhost/~/test

@cheatSheet_1031_p
# user home dir

@cheatSheet_1032_code
#jdbc:h2:tcp://localhost//data/test

@cheatSheet_1033_p
# absolute dir

@cheatSheet_1034_a
#Server start

@cheatSheet_1035_p
#:<code>java -cp *.jar org.h2.tools.Server</code> 

@cheatSheet_1036_a
#Settings

@cheatSheet_1037_code
#jdbc:h2:..;MODE=MySQL

@cheatSheet_1038_a
#compatibility (or HSQLDB,...)

@cheatSheet_1039_code
#jdbc:h2:..;TRACE_LEVEL_FILE=3

@cheatSheet_1040_a
#log to *.trace.db

@cheatSheet_1041_a
#Using the JDBC API

@cheatSheet_1042_a
#Connection Pool

@cheatSheet_1043_a
#Maven 2

@cheatSheet_1044_a
#Hibernate

@cheatSheet_1045_p
# hibernate.cfg.xml (or use the HSQLDialect): 

@cheatSheet_1046_a
#TopLink and Glassfish

@cheatSheet_1047_p
# Datasource class: <code>org.h2.jdbcx.JdbcDataSource</code>

@cheatSheet_1048_code
#oracle.toplink.essentials.platform.

@cheatSheet_1049_code
#database.H2Platform

@download_1000_h1
ダウンロード

@download_1001_h3
#Version 1.2.135 (2010-05-08)

@download_1002_a
Windows Installer

@download_1003_a
Platform-Independent Zip

@download_1004_h3
#Version 1.2.134 (2010-04-23, Last Stable)

@download_1005_a
Windows Installer

@download_1006_a
Platform-Independent Zip

@download_1007_h3
#Download Mirror and Older Versions

@download_1008_a
Platform-Independent Zip

@download_1009_h3
#Jar File

@download_1010_a
#Maven.org

@download_1011_a
#Sourceforge.net

@download_1012_a
#Latest Automated Build (not released)

@download_1013_h3
サブバージョンのソースリポジトリ

@download_1014_a
Google Code

@download_1015_p
# For details about changes, see the <a href="changelog.html">Change Log</a>. 

@download_1016_h3
#News and Project Information

@download_1017_a
#Atom Feed

@download_1018_a
#RSS Feed

@download_1019_a
#DOAP File

@download_1020_p
# (<a href="http://trac.usefulinc.com/doap">what is this</a>) 

@faq_1000_h1
F A Q

@faq_1001_a
# I Have a Problem or Feature Request

@faq_1002_a
# Are there Known Bugs? When is the Next Release?

@faq_1003_a
# Is this Database Engine Open Source?

@faq_1004_a
# My Query is Slow

@faq_1005_a
# How to Create a New Database?

@faq_1006_a
# How to Connect to a Database?

@faq_1007_a
# Where are the Database Files Stored?

@faq_1008_a
# What is the Size Limit (Maximum Size) of a Database?

@faq_1009_a
# Is it Reliable?

@faq_1010_a
# Why is Opening my Database Slow?

@faq_1011_a
# Column Names are Incorrect?

@faq_1012_a
# Float is Double?

@faq_1013_a
# Is the GCJ Version Stable? Faster?

@faq_1014_a
# How to Translate this Project?

@faq_1015_h3
#I Have a Problem or Feature Request

@faq_1016_p
# Please read the <a href="build.html#support">support checklist</a>. 

@faq_1017_h3
#Are there Known Bugs? When is the Next Release?

@faq_1018_p
# Usually, bugs get fixes as they are found. There is a release every few weeks. Here is the list of known and confirmed issues: 

@faq_1019_li
#Apache Harmony: there seems to be a bug in Harmony that affects H2. See <a href="https://issues.apache.org/jira/browse/HARMONY-6505">HARMONY-6505</a>. 

@faq_1020_li
#Tomcat and Glassfish 3 set most static fields (final or non-final) to <code>null</code> when unloading a web application. This can cause a <code>NullPointerException</code> in H2 versions 1.1.107 and older, and may still not work in newer versions. Please report it if you run into this issue. In Tomcat &gt;= 6.0 this behavior can be disabled by setting the system property <code>org.apache.catalina.loader.WebappClassLoader.ENABLE_CLEAR_REFERENCES=false</code>, however Tomcat may then run out of memory. A known workaround is to put the <code>h2*.jar</code> file in a shared <code>lib</code> directory (<code>common/lib</code>). 

@faq_1021_li
#Some problems have been found with right outer join. Internally, it is converted to left outer join, which does not always produce the same results as other databases when used in combination with other joins. 

@faq_1022_li
#When using Install4j before 4.1.4 on Linux and enabling <code>pack200</code>, the <code>h2*.jar</code> becomes corrupted by the install process, causing application failure. A workaround is to add an empty file <code>h2*.jar.nopack</code> next to the <code>h2*.jar</code> file. This problem is solved in Install4j 4.1.4. 

@faq_1023_p
# For a complete list, see <a href="http://code.google.com/p/h2database/issues/list">Open Issues</a>. 

@faq_1024_h3
このデータベースエンジンはオープンソースですか？

@faq_1025_p
# Yes. It is free to use and distribute, and the source code is included. See also under license. 

@faq_1026_h3
#My Query is Slow

@faq_1027_p
# Slow <code>SELECT</code> (or <code>DELETE, UPDATE, MERGE</code>) statement can have multiple reasons. Follow this checklist: 

@faq_1028_li
#Run <code>ANALYZE</code> (see documentation for details). 

@faq_1029_li
#Run the query with <code>EXPLAIN</code> and check if indexes are used (see documentation for details). 

@faq_1030_li
#If required, create additional indexes and try again using <code>ANALYZE</code> and <code>EXPLAIN</code>. 

@faq_1031_li
#If it doesn't help please report the problem. 

@faq_1032_h3
新規データベースの構築方法は？

@faq_1033_p
# By default, a new database is automatically created if it does not yet exist. See <a href="tutorial.html#creating_new_databases">Creating New Databases</a>. 

@faq_1034_h3
データベースへの接続方法は？

@faq_1035_p
# The database driver is <code>org.h2.Driver</code>, and the database URL starts with <code>jdbc:h2:</code>. To connect to a database using JDBC, use the following code: 

@faq_1036_h3
データベースのファイルはどこに保存されますか？

@faq_1037_p
# When using database URLs like <code>jdbc:h2:~/test</code>, the database is stored in the user directory. For Windows, this is usually <code>C:\Documents and Settings\&lt;userName&gt;</code>. If the base directory is not set (as in <code>jdbc:h2:test</code>), the database files are stored in the directory where the application is started (the current working directory). When using the H2 Console application from the start menu, this is <code>&lt;Installation Directory&gt;/bin</code>. The base directory can be set in the database URL. A fixed or relative path can be used. When using the URL <code>jdbc:h2:file:data/sample</code>, the database is stored in the directory <code>data</code> (relative to the current working directory). The directory is created automatically if it does not yet exist. It is also possible to use the fully qualified directory name (and for Windows, drive name). Example: <code>jdbc:h2:file:C:/data/test</code> 

@faq_1038_h3
#What is the Size Limit (Maximum Size) of a Database?

@faq_1039_p
# See <a href="advanced.html#limits_limitations">Limits and Limitations</a>. 

@faq_1040_h3
これは信頼できるデータベースですか？

@faq_1041_p
# That is not easy to say. It is still a quite new product. A lot of tests have been written, and the code coverage of these tests is very high. Randomized stress tests are run regularly. But there are probably still bugs that have not yet been found (as with most software). Some features are known to be dangerous, they are only supported for situations where performance is more important than reliability. Those dangerous features are: 

@faq_1042_li
#Using the transaction isolation level <code>READ_UNCOMMITTED</code> (<code>LOCK_MODE 0</code>) while at the same time using multiple connections. 

@faq_1043_li
#Disabling database file protection using <code>FILE_LOCK=NO</code> in the database URL. 

@faq_1044_li
#Disabling referential integrity using <code>SET REFERENTIAL_INTEGRITY FALSE</code>. 

@faq_1045_p
# In addition to that, running out of memory should be avoided. In older versions, OutOfMemory errors while using the database could corrupt a databases. 

@faq_1046_p
# Some areas of this database are not fully tested. When using one of those features for production, please ensure your use case is well tested (if possible with automated test cases). Those areas are: 

@faq_1047_li
#Platforms other than Windows XP, Linux, Mac OS X, or JVMs other than Sun 1.5 or 1.6 

@faq_1048_li
#The features <code>AUTO_SERVER</code> and <code>AUTO_RECONNECT</code> 

@faq_1049_li
#The file locking method 'Serialized' 

@faq_1050_li
#The MVCC (multi version concurrency) mode 

@faq_1051_li
#Cluster mode, 2-phase commit, savepoints 

@faq_1052_li
#24/7 operation 

@faq_1053_li
#Some operations on databases larger than 500 MB may be slower than expected 

@faq_1054_li
#The optimizer may not always select the best plan 

@faq_1055_li
#Fulltext search 

@faq_1056_li
#Operations on LOBs over 2 GB 

@faq_1057_p
# Areas considered experimental are: 

@faq_1058_li
#The PostgreSQL server 

@faq_1059_li
#Multi-threading within the engine using <code>SET MULTI_THREADED=1</code> 

@faq_1060_li
#Compatibility modes for other databases (only some features are implemented) 

@faq_1061_li
#The soft reference cache (CACHE_TYPE=SOFT_LRU). It might not improve performance, and out of memory issues have been reported. 

@faq_1062_p
# Some users have reported that after a power failure, the database cannot be opened sometimes. In this case, use a backup of the database or the Recover tool. Please report such problems. The plan is that the database automatically recovers in all situations. 

@faq_1063_h3
#Column Names are Incorrect?

@faq_1064_p
# For the query <code>SELECT ID AS X FROM TEST</code> the method <code>ResultSetMetaData.getColumnName()</code> returns <code>ID</code>, I expect it to return <code>X</code>. What's wrong? 

@faq_1065_p
# This is not a bug. According the the JDBC specification, the method <code>ResultSetMetaData.getColumnName()</code> should return the name of the column and not the alias name. If you need the alias name, use <a href="http://java.sun.com/javase/6/docs/api/java/sql/ResultSetMetaData.html#getColumnLabel(int)"><code>ResultSetMetaData.getColumnLabel()</code></a>. Some other database don't work like this yet (they don't follow the JDBC specification). If you need compatibility with those databases, use the <a href="features.html#compatibility">Compatibility Mode</a>, or set the system property <a href="../javadoc/org/h2/constant/SysProperties.html#h2.aliasColumnName"><code>h2.aliasColumnName</code></a>. 

@faq_1066_p
# This also applies to DatabaseMetaData calls that return a result set. The columns in the JDBC API are column labels, not column names. 

@faq_1067_h3
#Float is Double?

@faq_1068_p
# For a table defined as <code>CREATE TABLE TEST(X FLOAT)</code> the method <code>ResultSet.getObject()</code> returns a <code>java.lang.Double</code>, I expect it to return a <code>java.lang.Float</code>. What's wrong? 

@faq_1069_p
# This is not a bug. According the the JDBC specification, the JDBC data type <code>FLOAT</code> is equivalent to <code>DOUBLE</code>, and both are mapped to <code>java.lang.Double</code>. See also <a href="http://java.sun.com/j2se/1.5.0/docs/guide/jdbc/getstart/mapping.html#1055162"> Mapping SQL and Java Types - 8.3.10 FLOAT</a>.

@faq_1070_h3
#Why is Opening my Database Slow?

@faq_1071_p
# To find out what the problem is, use the H2 Console and click on "Test Connection" instead of "Login". After the "Login Successful" appears, click on it (it's a link). This will list the top stack traces. Then either analyze this yourself, or post those stack traces in the Google Group. 

@faq_1072_p
# To find out what the problem is, open the database in embedded mode using the H2 Console. This will print progress information. If you have many lines with 'Creating index' it is an indication that the database was not closed the last time. 

@faq_1073_p
# Other possible reasons are: the database is very big (many GB), or contains linked tables that are slow to open. 

@faq_1074_h3
#Is the GCJ Version Stable? Faster?

@faq_1075_p
# The GCJ version is not as stable as the Java version. When running the regression test with the GCJ version, sometimes the application just stops at what seems to be a random point without error message. Currently, the GCJ version is also slower than when using the Sun VM. However, the startup of the GCJ version is faster than when using a VM. 

@faq_1076_h3
このプロジェクトの翻訳方法は？

@faq_1077_p
# For more information, see <a href="build.html#translating">Build/Translating</a>. 

@features_1000_h1
特徴

@features_1001_a
# Feature List

@features_1002_a
# Comparison to Other Database Engines

@features_1003_a
# H2 in Use

@features_1004_a
# Connection Modes

@features_1005_a
# Database URL Overview

@features_1006_a
# Connecting to an Embedded (Local) Database

@features_1007_a
# In-Memory Databases

@features_1008_a
# Database Files Encryption

@features_1009_a
# Database File Locking

@features_1010_a
# Opening a Database Only if it Already Exists

@features_1011_a
# Closing a Database

@features_1012_a
# Ignore Unknown Settings

@features_1013_a
# Changing Other Settings when Opening a Connection

@features_1014_a
# Custom File Access Mode

@features_1015_a
# Multiple Connections

@features_1016_a
# Database File Layout

@features_1017_a
# Logging and Recovery

@features_1018_a
# Compatibility

@features_1019_a
# Auto-Reconnect

@features_1020_a
# Automatic Mixed Mode

@features_1021_a
# Page Size

@features_1022_a
# Using the Trace Options

@features_1023_a
# Using Other Logging APIs

@features_1024_a
# Read Only Databases

@features_1025_a
# Read Only Databases in Zip or Jar File

@features_1026_a
# Graceful Handling of Low Disk Space Situations

@features_1027_a
# Computed Columns / Function Based Index

@features_1028_a
# Multi-Dimensional Indexes

@features_1029_a
# Using Passwords

@features_1030_a
# User-Defined Functions and Stored Procedures

@features_1031_a
# Triggers

@features_1032_a
# Compacting a Database

@features_1033_a
# Cache Settings

@features_1034_h2
特徴一覧

@features_1035_h3
主な特徴

@features_1036_li
#Very fast database engine 

@features_1037_li
#Open source 

@features_1038_li
#Written in Java 

@features_1039_li
#Supports standard SQL, JDBC API 

@features_1040_li
#Embedded and Server mode, Clustering support 

@features_1041_li
#Strong security features 

@features_1042_li
#The PostgreSQL ODBC driver can be used 

@features_1043_li
#Multi version concurrency 

@features_1044_h3
追加された特徴

@features_1045_li
#Disk based or in-memory databases and tables, read-only database support, temporary tables 

@features_1046_li
#Transaction support (read committed and serializable transaction isolation), 2-phase-commit 

@features_1047_li
#Multiple connections, table level locking 

@features_1048_li
#Cost based optimizer, using a genetic algorithm for complex queries, zero-administration 

@features_1049_li
#Scrollable and updatable result set support, large result set, external result sorting, functions can return a result set 

@features_1050_li
#Encrypted database (AES or XTEA), SHA-256 password encryption, encryption functions, SSL 

@features_1051_h3
SQLサポート

@features_1052_li
#Support for multiple schemas, information schema 

@features_1053_li
#Referential integrity / foreign key constraints with cascade, check constraints 

@features_1054_li
#Inner and outer joins, subqueries, read only views and inline views 

@features_1055_li
#Triggers and Java functions / stored procedures 

@features_1056_li
#Many built-in functions, including XML and lossless data compression 

@features_1057_li
#Wide range of data types including large objects (BLOB/CLOB) and arrays 

@features_1058_li
#Sequence and autoincrement columns, computed columns (can be used for function based indexes) 

@features_1059_code
ORDER BY, GROUP BY, HAVING, UNION, LIMIT, TOP

@features_1060_li
#Collation support, users, roles 

@features_1061_li
#Compatibility modes for IBM DB2, Apache Derby, HSQLDB, MS SQL Server, MySQL, Oracle, and PostgreSQL. 

@features_1062_h3
セキュリティの特徴

@features_1063_li
#Includes a solution for the SQL injection problem 

@features_1064_li
#User password authentication uses SHA-256 and salt 

@features_1065_li
#For server mode connections, user passwords are never transmitted in plain text over the network (even when using insecure connections; this only applies to the TCP server and not to the H2 Console however; it also doesn't apply if you set the password in the database URL) 

@features_1066_li
#All database files (including script files that can be used to backup data) can be encrypted using AES-128 and XTEA encryption algorithms 

@features_1067_li
#The remote JDBC driver supports TCP/IP connections over SSL/TLS 

@features_1068_li
#The built-in web server supports connections over SSL/TLS 

@features_1069_li
#Passwords can be sent to the database using char arrays instead of Strings 

@features_1070_h3
他の特徴とツール

@features_1071_li
#Small footprint (smaller than 1 MB), low memory requirements 

@features_1072_li
#Multiple index types (b-tree, tree, hash) 

@features_1073_li
#Support for multi-dimensional indexes 

@features_1074_li
#CSV (comma separated values) file support 

@features_1075_li
#Support for linked tables, and a built-in virtual 'range' table 

@features_1076_code
#EXPLAIN PLAN

@features_1077_li
# support, sophisticated trace options 

@features_1078_li
#Database closing can be delayed or disabled to improve the performance 

@features_1079_li
#Web-based Console application (translated to many languages) with autocomplete 

@features_1080_li
#The database can generate SQL script files 

@features_1081_li
#Contains a recovery tool that can dump the contents of the database 

@features_1082_li
#Support for variables (for example to calculate running totals) 

@features_1083_li
#Automatic re-compilation of prepared statements 

@features_1084_li
#Uses a small number of database files 

@features_1085_li
#Uses a checksum for each record and log entry for data integrity 

@features_1086_li
#Well tested (high code coverage, randomized stress tests) 

@features_1087_h2
他のデータベースエンジンと比較する

@features_1088_th
特徴

@features_1089_th
H2

@features_1090_a
Derby

@features_1091_a
HSQLDB

@features_1092_a
MySQL

@features_1093_a
PostgreSQL

@features_1094_td
Pure Java

@features_1095_td
対応

@features_1096_td
対応

@features_1097_td
対応

@features_1098_td
非対応

@features_1099_td
非対応

@features_1100_td
エンベッドモード (Java)

@features_1101_td
対応

@features_1102_td
対応

@features_1103_td
対応

@features_1104_td
非対応

@features_1105_td
非対応

@features_1106_td
パフォーマンス (エンベッド)

@features_1107_td
速い

@features_1108_td
遅い

@features_1109_td
速い

@features_1110_td
該当なし

@features_1111_td
該当なし

@features_1112_td
#In-Memory Mode

@features_1113_td
対応

@features_1114_td
対応

@features_1115_td
対応

@features_1116_td
非対応

@features_1117_td
非対応

@features_1118_td
トランザクション分離

@features_1119_td
対応

@features_1120_td
対応

@features_1121_td
非対応

@features_1122_td
対応

@features_1123_td
対応

@features_1124_td
コストベースオプティマイザ

@features_1125_td
対応

@features_1126_td
対応

@features_1127_td
非対応

@features_1128_td
対応

@features_1129_td
対応

@features_1130_td
#Explain Plan

@features_1131_td
対応

@features_1132_td
非対応

@features_1133_td
対応

@features_1134_td
対応

@features_1135_td
対応

@features_1136_td
クラスタリング

@features_1137_td
対応

@features_1138_td
非対応

@features_1139_td
非対応

@features_1140_td
対応

@features_1141_td
対応

@features_1142_td
暗号化データベース

@features_1143_td
対応

@features_1144_td
対応

@features_1145_td
非対応

@features_1146_td
非対応

@features_1147_td
非対応

@features_1148_td
リンクテーブル

@features_1149_td
対応

@features_1150_td
非対応

@features_1151_td
#Partially *1

@features_1152_td
#Partially *2

@features_1153_td
非対応

@features_1154_td
ODBCドライバ

@features_1155_td
対応

@features_1156_td
非対応

@features_1157_td
非対応

@features_1158_td
対応

@features_1159_td
対応

@features_1160_td
フルテキストサーチ

@features_1161_td
対応

@features_1162_td
非対応

@features_1163_td
非対応

@features_1164_td
対応

@features_1165_td
対応

@features_1166_td
#User-Defined Datatypes

@features_1167_td
対応

@features_1168_td
非対応

@features_1169_td
非対応

@features_1170_td
対応

@features_1171_td
対応

@features_1172_td
データベースごとのファイル

@features_1173_td
少

@features_1174_td
多

@features_1175_td
少

@features_1176_td
多

@features_1177_td
多

@features_1178_td
テーブルレベルロック

@features_1179_td
対応

@features_1180_td
対応

@features_1181_td
非対応

@features_1182_td
対応

@features_1183_td
対応

@features_1184_td
#Row Level Locking

@features_1185_td
#Yes *9

@features_1186_td
対応

@features_1187_td
非対応

@features_1188_td
対応

@features_1189_td
対応

@features_1190_td
#Multi Version Concurrency

@features_1191_td
対応

@features_1192_td
非対応

@features_1193_td
非対応

@features_1194_td
対応

@features_1195_td
対応

@features_1196_td
#Role Based Security

@features_1197_td
対応

@features_1198_td
#Yes *3

@features_1199_td
対応

@features_1200_td
対応

@features_1201_td
対応

@features_1202_td
#Updatable Result Sets

@features_1203_td
対応

@features_1204_td
#Yes *7

@features_1205_td
非対応

@features_1206_td
対応

@features_1207_td
対応

@features_1208_td
#Sequences

@features_1209_td
対応

@features_1210_td
非対応

@features_1211_td
対応

@features_1212_td
非対応

@features_1213_td
対応

@features_1214_td
#Limit and Offset

@features_1215_td
対応

@features_1216_td
非対応

@features_1217_td
対応

@features_1218_td
対応

@features_1219_td
対応

@features_1220_td
#Temporary Tables

@features_1221_td
対応

@features_1222_td
#Yes *4

@features_1223_td
対応

@features_1224_td
対応

@features_1225_td
対応

@features_1226_td
#Information Schema

@features_1227_td
対応

@features_1228_td
#No *8

@features_1229_td
#No *8

@features_1230_td
対応

@features_1231_td
対応

@features_1232_td
#Computed Columns

@features_1233_td
対応

@features_1234_td
非対応

@features_1235_td
非対応

@features_1236_td
非対応

@features_1237_td
#Yes *6

@features_1238_td
#Case Insensitive Columns

@features_1239_td
対応

@features_1240_td
非対応

@features_1241_td
対応

@features_1242_td
対応

@features_1243_td
#Yes *6

@features_1244_td
#Custom Aggregate Functions

@features_1245_td
対応

@features_1246_td
非対応

@features_1247_td
非対応

@features_1248_td
対応

@features_1249_td
対応

@features_1250_td
フットプリント (jar/dll size)

@features_1251_td
#~1 MB *5

@features_1252_td
#~2 MB

@features_1253_td
#~700 KB

@features_1254_td
#~4 MB

@features_1255_td
#~6 MB

@features_1256_p
# *1 HSQLDB supports text tables.

@features_1257_p
# *2 MySQL supports linked MySQL tables under the name 'federated tables'.

@features_1258_p
# *3 Derby support for roles based security and password checking as an option.

@features_1259_p
# *4 Derby only supports global temporary tables.

@features_1260_p
# *5 The default H2 jar file contains debug information, jar files for other databases do not.

@features_1261_p
# *6 PostgreSQL supports functional indexes.

@features_1262_p
# *7 Derby only supports updatable result sets if the query is not sorted.

@features_1263_p
# *8 Derby and HSQLDB don't support standard compliant information schema tables.

@features_1264_p
# *9 H2 supports row level locks when using multi version concurrency. 

@features_1265_h3
DerbyとHSQLDB

@features_1266_p
# After an unexpected process termination (for example power failure), H2 can usually recover safely and automatically without any user interaction. For Derby and HSQLDB, some manual steps are required ('Another instance of Derby may have already booted the database' / 'The database is already in use by another process'). 

@features_1267_h3
DaffodilDbとOne$Db

@features_1268_p
# It looks like the development of this database has stopped. The last release was February 2006. 

@features_1269_h3
McKoi

@features_1270_p
# It looks like the development of this database has stopped. The last release was August 2004 

@features_1271_h2
#H2 in Use

@features_1272_p
# For a list of applications that work with or use H2, see: <a href="links.html">Links</a>. 

@features_1273_h2
接続モード

@features_1274_p
# The following connection modes are supported: 

@features_1275_li
#Embedded mode (local connections using JDBC) 

@features_1276_li
#Server mode (remote connections using JDBC or ODBC over TCP/IP) 

@features_1277_li
#Mixed mode (local and remote connections at the same time) 

@features_1278_h3
エンベッドモード

@features_1279_p
# In embedded mode, an application opens a database from within the same JVM using JDBC. This is the fastest and easiest connection mode. The disadvantage is that a database may only be open in one virtual machine (and class loader) at any time. As in all modes, both persistent and in-memory databases are supported. There is no limit on the number of database open concurrently, or on the number of open connections. 

@features_1280_h3
サーバーモード

@features_1281_p
# When using the server mode (sometimes called remote mode or client/server mode), an application opens a database remotely using the JDBC or ODBC API. A server needs to be started within the same or another virtual machine, or on another computer. Many applications can connect to the same database at the same time, by connecting to this server. Internally, the server process opens the database(s) in embedded mode. 

@features_1282_p
# The server mode is slower than the embedded mode, because all data is transferred over TCP/IP. As in all modes, both persistent and in-memory databases are supported. There is no limit on the number of database open concurrently per server, or on the number of open connections. 

@features_1283_h3
#Mixed Mode

@features_1284_p
# The mixed mode is a combination of the embedded and the server mode. The first application that connects to a database does that in embedded mode, but also starts a server so that other applications (running in different processes or virtual machines) can concurrently access the same data. The local connections are as fast as if the database is used in just the embedded mode, while the remote connections are a bit slower. 

@features_1285_p
# The server can be started and stopped from within the application (using the server API), or automatically (automatic mixed mode). When using the <a href="#auto_mixed_mode">automatic mixed mode</a>, all clients that want to connect to the database (no matter if it's an local or remote connection) can do so using the exact same database URL. 

@features_1286_h2
データベースURL概要

@features_1287_p
# This database supports multiple connection modes and connection settings. This is achieved using different database URLs. Settings in the URLs are not case sensitive. 

@features_1288_th
トピック

@features_1289_th
URLフォーマットと例

@features_1290_a
エンベッド (ローカル) 接続

@features_1291_td
# jdbc:h2:[file:][&lt;path&gt;]&lt;databaseName&gt;

@features_1292_td
# jdbc:h2:~/test

@features_1293_td
# jdbc:h2:file:/data/sample

@features_1294_td
# jdbc:h2:file:C:/data/sample (Windows only)

@features_1295_a
#In-memory (private)

@features_1296_td
jdbc:h2:mem:

@features_1297_a
#In-memory (named)

@features_1298_td
# jdbc:h2:mem:&lt;databaseName&gt;

@features_1299_td
# jdbc:h2:mem:test_mem 

@features_1300_a
#Server mode (remote connections)

@features_1301_a
# using TCP/IP

@features_1302_td
# jdbc:h2:tcp://&lt;server&gt;[:&lt;port&gt;]/[&lt;path&gt;]&lt;databaseName&gt;

@features_1303_td
# jdbc:h2:tcp://localhost/~/test

@features_1304_td
# jdbc:h2:tcp://dbserv:8084/~/sample 

@features_1305_a
#Server mode (remote connections)

@features_1306_a
# using SSL/TLS

@features_1307_td
# jdbc:h2:ssl://&lt;server&gt;[:&lt;port&gt;]/&lt;databaseName&gt;

@features_1308_td
# jdbc:h2:ssl://secureserv:8085/~/sample; 

@features_1309_a
#Using encrypted files

@features_1310_td
# jdbc:h2:&lt;url&gt;;CIPHER=[AES|XTEA]

@features_1311_td
# jdbc:h2:ssl://secureserv/~/testdb;CIPHER=AES

@features_1312_td
# jdbc:h2:file:~/secure;CIPHER=XTEA

@features_1313_a
#File locking methods

@features_1314_td
# jdbc:h2:&lt;url&gt;;FILE_LOCK={NO|FILE|SOCKET}

@features_1315_td
# jdbc:h2:file:~/quickAndDirty;FILE_LOCK=NO

@features_1316_td
# jdbc:h2:file:~/private;CIPHER=XTEA;FILE_LOCK=SOCKET

@features_1317_a
#Only open if it already exists

@features_1318_td
# jdbc:h2:&lt;url&gt;;IFEXISTS=TRUE

@features_1319_td
# jdbc:h2:file:~/sample;IFEXISTS=TRUE

@features_1320_a
#Don't close the database when the VM exits

@features_1321_td
# jdbc:h2:&lt;url&gt;;DB_CLOSE_ON_EXIT=FALSE 

@features_1322_a
#Execute SQL on connection

@features_1323_td
# jdbc:h2:&lt;url&gt;;INIT=RUNSCRIPT FROM '~/create.sql'

@features_1324_td
# jdbc:h2:file:~/sample;INIT=RUNSCRIPT FROM '~/create.sql'\\;RUNSCRIPT FROM '~/populate.sql'

@features_1325_a
#User name and/or password

@features_1326_td
# jdbc:h2:&lt;url&gt;[;USER=&lt;username&gt;][;PASSWORD=&lt;value&gt;]

@features_1327_td
# jdbc:h2:file:~/sample;USER=sa;PASSWORD=123

@features_1328_a
#Debug trace settings

@features_1329_td
# jdbc:h2:&lt;url&gt;;TRACE_LEVEL_FILE=&lt;level 0..3&gt;

@features_1330_td
# jdbc:h2:file:~/sample;TRACE_LEVEL_FILE=3

@features_1331_a
#Ignore unknown settings

@features_1332_td
# jdbc:h2:&lt;url&gt;;IGNORE_UNKNOWN_SETTINGS=TRUE

@features_1333_a
#Custom file access mode

@features_1334_td
# jdbc:h2:&lt;url&gt;;ACCESS_MODE_DATA=rws

@features_1335_a
#Database in a zip file

@features_1336_td
# jdbc:h2:zip:&lt;zipFileName&gt;!/&lt;databaseName&gt;

@features_1337_td
# jdbc:h2:zip:~/db.zip!/test 

@features_1338_a
#Compatibility mode

@features_1339_td
# jdbc:h2:&lt;url&gt;;MODE=&lt;databaseType&gt;

@features_1340_td
# jdbc:h2:~/test;MODE=MYSQL 

@features_1341_a
#Auto-reconnect

@features_1342_td
# jdbc:h2:&lt;url&gt;;AUTO_RECONNECT=TRUE

@features_1343_td
# jdbc:h2:tcp://localhost/~/test;AUTO_RECONNECT=TRUE 

@features_1344_a
#Automatic mixed mode

@features_1345_td
# jdbc:h2:&lt;url&gt;;AUTO_SERVER=TRUE

@features_1346_td
# jdbc:h2:~/test;AUTO_SERVER=TRUE 

@features_1347_a
#Page size

@features_1348_td
# jdbc:h2:&lt;url&gt;;PAGE_SIZE=512

@features_1349_a
#Changing other settings

@features_1350_td
# jdbc:h2:&lt;url&gt;;&lt;setting&gt;=&lt;value&gt;[;&lt;setting&gt;=&lt;value&gt;...]

@features_1351_td
# jdbc:h2:file:~/sample;TRACE_LEVEL_SYSTEM_OUT=3

@features_1352_h2
エンベッド (ローカル) データベースに接続

@features_1353_p
# The database URL for connecting to a local database is <code>jdbc:h2:[file:][&lt;path&gt;]&lt;databaseName&gt;</code>. The prefix <code>file:</code> is optional. If no or only a relative path is used, then the current working directory is used as a starting point. The case sensitivity of the path and database name depend on the operating system, however it is recommended to use lowercase letters only. The database name must be at least three characters long (a limitation of <code>File.createTempFile</code>). To point to the user home directory, use <code>~/</code>, as in: <code>jdbc:h2:~/test</code>. 

@features_1354_h2
#In-Memory Databases

@features_1355_p
# For certain use cases (for example: rapid prototyping, testing, high performance operations, read-only databases), it may not be required to persist data, or persist changes to the data. This database supports the in-memory mode, where the data is not persisted. 

@features_1356_p
# In some cases, only one connection to a in-memory database is required. This means the database to be opened is private. In this case, the database URL is <code>jdbc:h2:mem:</code> Opening two connections within the same virtual machine means opening two different (private) databases. 

@features_1357_p
# Sometimes multiple connections to the same in-memory database are required. In this case, the database URL must include a name. Example: <code>jdbc:h2:mem:db1</code>. Accessing the same database in this way only works within the same virtual machine and class loader environment. 

@features_1358_p
# In-memory can be accessed remotely (or from multiple processes in the same machine) using TCP/IP or SSL/TLS. An example database URL is: <code>jdbc:h2:tcp://localhost/mem:db1</code>. 

@features_1359_p
# By default, closing the last connection to a database closes the database. For an in-memory database, this means the content is lost. To keep the database open, add <code>;DB_CLOSE_DELAY=-1</code> to the database URL. To keep the content of an in-memory database as long as the virtual machine is alive, use <code>jdbc:h2:mem:test;DB_CLOSE_DELAY=-1</code>. 

@features_1360_h2
#Database Files Encryption

@features_1361_p
# The database files can be encrypted. Two encryption algorithms are supported: AES and XTEA. To use file encryption, you need to specify the encryption algorithm (the 'cipher') and the file password (in addition to the user password) when connecting to the database. 

@features_1362_h3
#Creating a New Database with File Encryption

@features_1363_p
# By default, a new database is automatically created if it does not exist yet. To create an encrypted database, connect to it as it would already exist. 

@features_1364_h3
#Connecting to an Encrypted Database

@features_1365_p
# The encryption algorithm is set in the database URL, and the file password is specified in the password field, before the user password. A single space separates the file password and the user password; the file password itself may not contain spaces. File passwords and user passwords are case sensitive. Here is an example to connect to a password-encrypted database: 

@features_1366_h3
#Encrypting or Decrypting a Database

@features_1367_p
# To encrypt an existing database, use the <code>ChangeFileEncryption</code> tool. This tool can also decrypt an encrypted database, or change the file encryption key. The tool is available from within the H2 Console in the tools section, or you can run it from the command line. The following command line will encrypt the database <code>test</code> in the user home directory with the file password <code>filepwd</code> and the encryption algorithm AES: 

@features_1368_h2
データベースファイルロック

@features_1369_p
# Whenever a database is opened, a lock file is created to signal other processes that the database is in use. If database is closed, or if the process that opened the database terminates, this lock file is deleted. 

@features_1370_p
# The following file locking methods are implemented: 

@features_1371_li
#The default method is 'file' and uses a watchdog thread to protect the database file. The watchdog reads the lock file each second. 

@features_1372_li
#The second method is 'socket' and opens a server socket. The socket method does not require reading the lock file every second. The socket method should only be used if the database files are only accessed by one (and always the same) computer. 

@features_1373_li
#It is also possible to open the database without file locking; in this case it is up to the application to protect the database files. 

@features_1374_p
# To open the database with a different file locking method, use the parameter <code>FILE_LOCK</code>. The following code opens the database with the 'socket' locking method: 

@features_1375_p
# The following code forces the database to not create a lock file at all. Please note that this is unsafe as another process is able to open the same database, possibly leading to data corruption: 

@features_1376_p
# For more information about the algorithms, see <a href="advanced.html#file_locking_protocols">Advanced / File Locking Protocols</a>. 

@features_1377_h2
すでに存在する場合のみ、データベースを開く

@features_1378_p
# By default, when an application calls <code>DriverManager.getConnection(url, ...)</code> and the database specified in the URL does not yet exist, a new (empty) database is created. In some situations, it is better to restrict creating new databases, and only allow to open existing databases. To do this, add <code>;IFEXISTS=TRUE</code> to the database URL. In this case, if the database does not already exist, an exception is thrown when trying to connect. The connection only succeeds when the database already exists. The complete URL may look like this: 

@features_1379_h2
#Closing a Database

@features_1380_h3
データベースの遅延終了

@features_1381_p
# Usually, a database is closed when the last connection to it is closed. In some situations this slows down the application, for example when it is not possible to keep at least one connection open. The automatic closing of a database can be delayed or disabled with the SQL statement <code>SET DB_CLOSE_DELAY &lt;seconds&gt;</code>. The parameter &lt;seconds&gt; specifies the number of seconds to keep a database open after the last connection to it was closed. The following statement will keep a database open for 10 seconds after the last connection was closed: 

@features_1382_p
# The value -1 means the database is not closed automatically. The value 0 is the default and means the database is closed when the last connection is closed. This setting is persistent and can be set by an administrator only. It is possible to set the value in the database URL: <code>jdbc:h2:~/test;DB_CLOSE_DELAY=10</code>. 

@features_1383_h3
#Don't Close a Database when the VM Exits

@features_1384_p
# By default, a database is closed when the last connection is closed. However, if it is never closed, the database is closed when the virtual machine exits normally, using a shutdown hook. In some situations, the database should not be closed in this case, for example because the database is still used at virtual machine shutdown (to store the shutdown process in the database for example). For those cases, the automatic closing of the database can be disabled in the database URL. The first connection (the one that is opening the database) needs to set the option in the database URL (it is not possible to change the setting afterwards). The database URL to disable database closing on exit is: 

@features_1385_h2
#Execute SQL on Connection

@features_1386_p
# Sometimes, particularly for in-memory databases, it is useful to be able to execute DDL or DML commands automatically when a client connects to a database. This functionality is enabled via the INIT property. Note that multiple commands may be passed to INIT, but the semicolon delimiter must be escaped, as in the example below. 

@features_1387_h2
未知の設定を無視

@features_1388_p
# Some applications (for example OpenOffice.org Base) pass some additional parameters when connecting to the database. Why those parameters are passed is unknown. The parameters <code>PREFERDOSLIKELINEENDS</code> and <code>IGNOREDRIVERPRIVILEGES</code> are such examples; they are simply ignored to improve the compatibility with OpenOffice.org. If an application passes other parameters when connecting to the database, usually the database throws an exception saying the parameter is not supported. It is possible to ignored such parameters by adding <code>;IGNORE_UNKNOWN_SETTINGS=TRUE</code> to the database URL. 

@features_1389_h2
接続が開始された時に他の設定を変更する

@features_1390_p
# In addition to the settings already described, other database settings can be passed in the database URL. Adding <code>;setting=value</code> at the end of a database URL is the same as executing the statement <code>SET setting value</code> just after connecting. For a list of supported settings, see <a href="grammar.html">SQL Grammar</a>. 

@features_1391_h2
カスタムファイル アクセスモード

@features_1392_p
# Usually, the database opens the database file with the access mode <code>rw</code>, meaning read-write (except for read only databases, where the mode <code>r</code> is used). To open a database in read-only mode if the database file is not read-only, use <code>ACCESS_MODE_DATA=r</code>. Also supported are <code>rws</code> and <code>rwd</code>. This setting must be specified in the database URL: 

@features_1393_p
# For more information see <a href="advanced.html#durability_problems">Durability Problems</a>. On many operating systems the access mode <code>rws</code> does not guarantee that the data is written to the disk. 

@features_1394_h2
複数の接続

@features_1395_h3
同時に複数のデータベースを開く

@features_1396_p
# An application can open multiple databases at the same time, including multiple connections to the same database. The number of open database is only limited by the memory available. 

@features_1397_h3
>同じデータベースへの複数の接続: クライアント/サーバー

@features_1398_p
# If you want to access the same database at the same time from different processes or computers, you need to use the client / server mode. In this case, one process acts as the server, and the other processes (that could reside on other computers as well) connect to the server via TCP/IP (or SSL/TLS over TCP/IP for improved security). 

@features_1399_h3
マルチスレッドサポート

@features_1400_p
# This database is multithreading-safe. That means, if an application is multi-threaded, it does not need to worry about synchronizing access to the database. Internally, most requests to the same database are synchronized. That means an application can use multiple threads that access the same database at the same time, however if one thread executes a long running query, the other threads need to wait. 

@features_1401_p
# An application should normally use one connection per thread. This database synchronizes access to the same connection, but other databases may not do this. 

@features_1402_h3
ロック、ロックタイムアウト、デッドロック

@features_1403_p
# The database uses table level locks to give each connection a consistent state of the data. There are two kinds of locks: read locks (shared locks) and write locks (exclusive locks). All locks are released when the transaction commits or rolls back. When using the default transaction isolation level 'read committed', read locks are already released after each statement. 

@features_1404_p
# If a connection wants to reads from a table, and there is no write lock on the table, then a read lock is added to the table. If there is a write lock, then this connection waits for the other connection to release the lock. If a connection cannot get a lock for a specified time, then a lock timeout exception is thrown. 

@features_1405_p
# Usually, <code>SELECT</code> statements will generate read locks. This includes subqueries. Statements that modify data use write locks. It is also possible to lock a table exclusively without modifying data, using the statement <code>SELECT ... FOR UPDATE</code>. The statements <code>COMMIT</code> and <code>ROLLBACK</code> releases all open locks. The commands <code>SAVEPOINT</code> and <code>ROLLBACK TO SAVEPOINT</code> don't affect locks. The locks are also released when the autocommit mode changes, and for connections with autocommit set to true (this is the default), locks are released after each statement. The following statements generate locks: 

@features_1406_th
ロックの種類

@features_1407_th
SQLステートメント

@features_1408_td
Read

@features_1409_td
#SELECT * FROM TEST;

@features_1410_td
# CALL SELECT MAX(ID) FROM TEST;

@features_1411_td
# SCRIPT;

@features_1412_td
Write

@features_1413_td
#SELECT * FROM TEST WHERE 1=0 FOR UPDATE;

@features_1414_td
Write

@features_1415_td
#INSERT INTO TEST VALUES(1, 'Hello');

@features_1416_td
# INSERT INTO TEST SELECT * FROM TEST;

@features_1417_td
# UPDATE TEST SET NAME='Hi';

@features_1418_td
# DELETE FROM TEST;

@features_1419_td
Write

@features_1420_td
#ALTER TABLE TEST ...;

@features_1421_td
# CREATE INDEX ... ON TEST ...;

@features_1422_td
# DROP INDEX ...;

@features_1423_p
# The number of seconds until a lock timeout exception is thrown can be set separately for each connection using the SQL command <code>SET LOCK_TIMEOUT &lt;milliseconds&gt;</code>. The initial lock timeout (that is the timeout used for new connections) can be set using the SQL command <code>SET DEFAULT_LOCK_TIMEOUT &lt;milliseconds&gt;</code>. The default lock timeout is persistent. 

@features_1424_h2
データベースファイルレイアウト

@features_1425_p
# The following files are created for persistent databases: 

@features_1426_th
ファイル名

@features_1427_th
説明

@features_1428_th
ファイル数

@features_1429_td
# test.h2.db 

@features_1430_td
# Database file.

@features_1431_td
# Contains the transaction log, indexes, and data for all tables.

@features_1432_td
# Format: <code>&lt;database&gt;.h2.db</code> 

@features_1433_td
# 1 per database 

@features_1434_td
# test.lock.db 

@features_1435_td
# Database lock file.

@features_1436_td
# Automatically (re-)created while the database is in use.

@features_1437_td
# Format: <code>&lt;database&gt;.lock.db</code> 

@features_1438_td
# 1 per database (only if in use) 

@features_1439_td
# test.trace.db 

@features_1440_td
# Trace file (if the trace option is enabled).

@features_1441_td
# Contains trace information.

@features_1442_td
# Format: <code>&lt;database&gt;.trace.db</code>

@features_1443_td
# Renamed to <code>&lt;database&gt;.trace.db.old</code> is too big. 

@features_1444_td
# 0 or 1 per database 

@features_1445_td
# test.lobs.db/* 

@features_1446_td
# Directory containing one file for each

@features_1447_td
# BLOB or CLOB value larger than a certain size.

@features_1448_td
# Format: <code>&lt;id&gt;.t&lt;tableId&gt;.lob.db</code> 

@features_1449_td
# 1 per large object 

@features_1450_td
# test.123.temp.db 

@features_1451_td
# Temporary file.

@features_1452_td
# Contains a temporary blob or a large result set.

@features_1453_td
# Format: <code>&lt;database&gt;.&lt;id&gt;.temp.db</code> 

@features_1454_td
# 1 per object 

@features_1455_h3
データベースファイルの移動と改名

@features_1456_p
# Database name and location are not stored inside the database files. 

@features_1457_p
# While a database is closed, the files can be moved to another directory, and they can be renamed as well (as long as all files of the same database start with the same name and the respective extensions are unchanged). 

@features_1458_p
# As there is no platform specific data in the files, they can be moved to other operating systems without problems. 

@features_1459_h3
バックアップ

@features_1460_p
# When the database is closed, it is possible to backup the database files. Please note that index files do not need to be backed up, because they contain redundant data, and will be recreated automatically if they don't exist. 

@features_1461_p
# To backup data while the database is running, the SQL command <code>SCRIPT</code> can be used. 

@features_1462_h2
ログとリカバリー

@features_1463_p
# Whenever data is modified in the database and those changes are committed, the changes are written to the transaction log (except for in-memory objects). The changes to the main data area itself are usually written later on, to optimize disk access. If there is a power failure, the main data area is not up-to-date, but because the changes are in the transaction log, the next time the database is opened, the changes are re-applied automatically. 

@features_1464_h2
互換性

@features_1465_p
# All database engines behave a little bit different. Where possible, H2 supports the ANSI SQL standard, and tries to be compatible to other databases. There are still a few differences however: 

@features_1466_p
# In MySQL text columns are case insensitive by default, while in H2 they are case sensitive. However H2 supports case insensitive columns as well. To create the tables with case insensitive texts, append <code>IGNORECASE=TRUE</code> to the database URL (example: <code>jdbc:h2:~/test;IGNORECASE=TRUE</code>). 

@features_1467_h3
互換モード

@features_1468_p
# For certain features, this database can emulate the behavior of specific databases. Not all features or differences of those databases are implemented. Here is the list of currently supported modes and the differences to the regular mode: 

@features_1469_h3
#DB2 Compatibility Mode

@features_1470_p
# To use the IBM DB2 mode, use the database URL <code>jdbc:h2:~/test;MODE=DB2</code> or the SQL statement <code>SET MODE DB2</code>. 

@features_1471_li
#For aliased columns, <code>ResultSetMetaData.getColumnName()</code> returns the alias name and <code>getTableName()</code> returns <code>null</code>. 

@features_1472_li
#Support for the syntax <code>[OFFSET .. ROW] [FETCH ... ONLY]</code> as an alternative for <code>LIMIT .. OFFSET</code>. 

@features_1473_li
#Concatenating <code>NULL</code> with another value results in the other value. 

@features_1474_h3
#Derby Compatibility Mode

@features_1475_p
# To use the Apache Derby mode, use the database URL <code>jdbc:h2:~/test;MODE=Derby</code> or the SQL statement <code>SET MODE Derby</code>. 

@features_1476_li
#For aliased columns, <code>ResultSetMetaData.getColumnName()</code> returns the alias name and <code>getTableName()</code> returns <code>null</code>. 

@features_1477_li
#For unique indexes, <code>NULL</code> is distinct. That means only one row with <code>NULL</code> in one of the columns is allowed. 

@features_1478_li
#Concatenating <code>NULL</code> with another value results in the other value. 

@features_1479_h3
#HSQLDB Compatibility Mode

@features_1480_p
# To use the HSQLDB mode, use the database URL <code>jdbc:h2:~/test;MODE=HSQLDB</code> or the SQL statement <code>SET MODE HSQLDB</code>. 

@features_1481_li
#For aliased columns, <code>ResultSetMetaData.getColumnName()</code> returns the alias name and <code>getTableName()</code> returns <code>null</code>. 

@features_1482_li
#When converting the scale of decimal data, the number is only converted if the new scale is smaller than the current scale. Usually, the scale is converted and 0s are added if required. 

@features_1483_li
#For unique indexes, <code>NULL</code> is distinct. That means only one row with <code>NULL</code> in one of the columns is allowed. 

@features_1484_li
#Text can be concatenated using '+'. 

@features_1485_h3
#MS SQL Server Compatibility Mode

@features_1486_p
# To use the MS SQL Server mode, use the database URL <code>jdbc:h2:~/test;MODE=MSSQLServer</code> or the SQL statement <code>SET MODE MSSQLServer</code>. 

@features_1487_li
#For aliased columns, <code>ResultSetMetaData.getColumnName()</code> returns the alias name and <code>getTableName()</code> returns <code>null</code>. 

@features_1488_li
#Identifiers may be quoted using square brackets as in <code>[Test]</code>. 

@features_1489_li
#For unique indexes, <code>NULL</code> is distinct. That means only one row with <code>NULL</code> in one of the columns is allowed. 

@features_1490_li
#Concatenating <code>NULL</code> with another value results in the other value. 

@features_1491_li
#Text can be concatenated using '+'. 

@features_1492_h3
#MySQL Compatibility Mode

@features_1493_p
# To use the MySQL mode, use the database URL <code>jdbc:h2:~/test;MODE=MySQL</code> or the SQL statement <code>SET MODE MySQL</code>. 

@features_1494_li
#When inserting data, if a column is defined to be <code>NOT NULL</code> and <code>NULL</code> is inserted, then a 0 (or empty string, or the current timestamp for timestamp columns) value is used. Usually, this operation is not allowed and an exception is thrown. 

@features_1495_li
#Creating indexes in the <code>CREATE TABLE</code> statement is allowed. 

@features_1496_li
#Meta data calls return identifiers in lower case. 

@features_1497_li
#When converting a floating point number to an integer, the fractional digits are not truncated, but the value is rounded. 

@features_1498_li
#Concatenating <code>NULL</code> with another value results in the other value. 

@features_1499_h3
#Oracle Compatibility Mode

@features_1500_p
# To use the Oracle mode, use the database URL <code>jdbc:h2:~/test;MODE=Oracle</code> or the SQL statement <code>SET MODE Oracle</code>. 

@features_1501_li
#For aliased columns, <code>ResultSetMetaData.getColumnName()</code> returns the alias name and <code>getTableName()</code> returns <code>null</code>. 

@features_1502_li
#When using unique indexes, multiple rows with <code>NULL</code> in all columns are allowed, however it is not allowed to have multiple rows with the same values otherwise. 

@features_1503_li
#Concatenating <code>NULL</code> with another value results in the other value. 

@features_1504_h3
#PostgreSQL Compatibility Mode

@features_1505_p
# To use the PostgreSQL mode, use the database URL <code>jdbc:h2:~/test;MODE=PostgreSQL</code> or the SQL statement <code>SET MODE PostgreSQL</code>. 

@features_1506_li
#For aliased columns, <code>ResultSetMetaData.getColumnName()</code> returns the alias name and <code>getTableName()</code> returns <code>null</code>. 

@features_1507_li
#When converting a floating point number to an integer, the fractional digits are not be truncated, but the value is rounded. 

@features_1508_li
#The system columns <code>CTID</code> and <code>OID</code> are supported. 

@features_1509_h2
#Auto-Reconnect

@features_1510_p
# The auto-reconnect feature causes the JDBC driver to reconnect to the database if the connection is lost. The automatic re-connect only occurs when auto-commit is enabled; if auto-commit is disabled, an exception is thrown. To enable this mode, append <code>;AUTO_RECONNECT=TRUE</code> to the database URL. 

@features_1511_p
# Re-connecting will open a new session. After an automatic re-connect, variables and local temporary tables definitions (excluding data) are re-created. The contents of the system table <code>INFORMATION_SCHEMA.SESSION_STATE</code> contains all client side state that is re-created. 

@features_1512_p
# If another connection uses the database in exclusive mode (enabled using <code>SET EXCLUSIVE 1</code> or <code>SET EXCLUSIVE 2</code>), then this connection will try to re-connect until the exclusive mode ends. 

@features_1513_h2
#Automatic Mixed Mode

@features_1514_p
# Multiple processes can access the same database without having to start the server manually. To do that, append <code>;AUTO_SERVER=TRUE</code> to the database URL. You can use the same database URL independent of whether the database is already open or not. 

@features_1515_p
# When using this mode, the first connection to the database is made in embedded mode, and additionally a server is started internally (as a daemon thread). If the database is already open in another process, the server mode is used automatically. 

@features_1516_p
# The application that opens the first connection to the database uses the embedded mode, which is faster than the server mode. Therefore the main application should open the database first if possible. The first connection automatically starts a server on a random port. This server allows remote connections, however only to this database (to ensure that, the client reads <code>.lock.db</code> file and sends the the random key that is stored there to the server). When the first connection is closed, the server stops. If other (remote) connections are still open, one of them will then start a server (auto-reconnect is enabled automatically). 

@features_1517_p
# All processes need to have access to the database files. If the first connection is closed (the connection that started the server), open transactions of other connections will be rolled back (this may not be a problem if you don't disable autocommit). Explicit client/server connections (using <code>jdbc:h2:tcp://</code> or <code>ssl://</code>) are not supported. This mode is not supported for in-memory databases. 

@features_1518_p
# Here is an example how to use this mode. Application 1 and 2 are not necessarily started on the same computer, but they need to have access to the database files. Application 1 and 2 are typically two different processes (however they could run within the same process). 

@features_1519_h2
#Page Size

@features_1520_p
# The page size for new databases is 2 KB (2048), unless the system property <code>h2.pageSize</code> is set to a different value, or the page size is set explicitly in the database URL using <code>PAGE_SIZE=</code>. The page size of existing databases can not be changed. 

@features_1521_h2
トレースオプションを使用する

@features_1522_p
# To find problems in an application, it is sometimes good to see what database operations where executed. This database offers the following trace features: 

@features_1523_li
#Trace to <code>System.out</code> and/or to a file 

@features_1524_li
#Support for trace levels <code>OFF, ERROR, INFO, DEBUG</code> 

@features_1525_li
#The maximum size of the trace file can be set 

@features_1526_li
#It is possible to generate Java source code from the trace file 

@features_1527_li
#Trace can be enabled at runtime by manually creating a file 

@features_1528_h3
トレースオプション

@features_1529_p
# The simplest way to enable the trace option is setting it in the database URL. There are two settings, one for <code>System.out</code> (<code>TRACE_LEVEL_SYSTEM_OUT</code>) tracing, and one for file tracing (<code>TRACE_LEVEL_FILE</code>). The trace levels are 0 for <code>OFF</code>, 1 for <code>ERROR</code> (the default), 2 for <code>INFO</code>, and 3 for <code>DEBUG</code>. A database URL with both levels set to <code>DEBUG</code> is: 

@features_1530_p
# The trace level can be changed at runtime by executing the SQL command <code>SET TRACE_LEVEL_SYSTEM_OUT level</code> (for <code>System.out</code> tracing) or <code>SET TRACE_LEVEL_FILE level</code> (for file tracing). Example: 

@features_1531_h3
トレースファイルの最大サイズを設定

@features_1532_p
# When using a high trace level, the trace file can get very big quickly. The default size limit is 16 MB, if the trace file exceeds this limit, it is renamed to <code>.old</code> and a new file is created. If another such file exists, it is deleted. To limit the size to a certain number of megabytes, use <code>SET TRACE_MAX_FILE_SIZE mb</code>. Example: 

@features_1533_h3
Javaコード生成

@features_1534_p
# When setting the trace level to <code>INFO</code> or <code>DEBUG</code>, Java source code is generated as well. This simplifies reproducing problems. The trace file looks like this: 

@features_1535_p
# To filter the Java source code, use the <code>ConvertTraceFile</code> tool as follows: 

@features_1536_p
# The generated file <code>Test.java</code> will contain the Java source code. The generated source code may be too large to compile (the size of a Java method is limited). If this is the case, the source code needs to be split in multiple methods. The password is not listed in the trace file and therefore not included in the source code. 

@features_1537_h2
#Using Other Logging APIs

@features_1538_p
# By default, this database uses its own native 'trace' facility. This facility is called 'trace' and not 'log' within this database to avoid confusion with the transaction log. Trace messages can be written to both file and <code>System.out</code>. In most cases, this is sufficient, however sometimes it is better to use the same facility as the application, for example Log4j. To do that, this database support SLF4J. 

@features_1539_a
#SLF4J

@features_1540_p
# is a simple facade for various logging APIs and allows to plug in the desired implementation at deployment time. SLF4J supports implementations such as Logback, Log4j, Jakarta Commons Logging (JCL), Java logging, x4juli, and Simple Log. 

@features_1541_p
# To enable SLF4J, set the file trace level to 4 in the database URL: 

@features_1542_p
# Changing the log mechanism is not possible after the database is open, that means executing the SQL statement <code>SET TRACE_LEVEL_FILE 4</code> when the database is already open will not have the desired effect. To use SLF4J, all required jar files need to be in the classpath. If it does not work, check the file <code>&lt;database&gt;.trace.db</code> for error messages. 

@features_1543_h2
読み取り専用データベース

@features_1544_p
# If the database files are read-only, then the database is read-only as well. It is not possible to create new tables, add or modify data in this database. Only <code>SELECT</code> and <code>CALL</code> statements are allowed. To create a read-only database, close the database. Then, make the database file read-only. When you open the database now, it is read-only. There are two ways an application can find out whether database is read-only: by calling <code>Connection.isReadOnly()</code> or by executing the SQL statement <code>CALL READONLY()</code>. 

@features_1545_p
# Using the <a href="#custom_access_mode">Custom Access Mode</a> <code>r</code> the database can also be opened in read-only mode, even if the database file is not read only. 

@features_1546_h2
#Read Only Databases in Zip or Jar File

@features_1547_p
# To create a read-only database in a zip file, first create a regular persistent database, and then create a backup. The database must not have pending changes, that means you need to close all connections to the database first. If you are using a database named <code>test</code>, an easy way to create a zip file is using the <code>Backup</code> tool. You can start the tool from the command line, or from within the H2 Console (Tools - Backup). Please note that the database must be closed when the backup is created. Therefore, the SQL statement <code>BACKUP TO</code> can not be used. 

@features_1548_p
# When the zip file is created, you can open the database in the zip file using the following database URL: 

@features_1549_p
# Databases in zip files are read-only. The performance for some queries will be slower than when using a regular database, because random access in zip files is not supported (only streaming). How much this affects the performance depends on the queries and the data. The database is not read in memory; therefore large databases are supported as well. The same indexes are used as when using a regular database. 

@features_1550_h2
ディスクスペースが少ない状況での正しい取り扱い

@features_1551_p
# If the database needs more disk space, it calls the database event listener if one is installed. The application may then delete temporary files, or display a message and wait until the user has resolved the problem. To install a listener, run the SQL statement <code>SET DATABASE_EVENT_LISTENER</code> or use a database URL of the form <code>jdbc:h2:~/test;DATABASE_EVENT_LISTENER='com.acme.DbListener'</code> (the quotes around the class name are required). See also the <code>DatabaseEventListener</code> API. 

@features_1552_h3
破損したデータベースを開く

@features_1553_p
# If a database cannot be opened because the boot info (the SQL script that is run at startup) is corrupted, then the database can be opened by specifying a database event listener. The exceptions are logged, but opening the database will continue. 

@features_1554_h2
computed column / ベースインデックスの機能

@features_1555_p
# Function indexes are not directly supported by this database, but they can be emulated by using computed columns. For example, if an index on the upper-case version of a column is required, create a computed column with the upper-case version of the original column, and create an index for this column: 

@features_1556_p
# When inserting data, it is not required (and not allowed) to specify a value for the upper-case version of the column, because the value is generated. But you can use the column when querying the table: 

@features_1557_h2
多次元インデックス

@features_1558_p
# A tool is provided to execute efficient multi-dimension (spatial) range queries. This database does not support a specialized spatial index (R-Tree or similar). Instead, the B-Tree index is used. For each record, the multi-dimensional key is converted (mapped) to a single dimensional (scalar) value. This value specifies the location on a space-filling curve. 

@features_1559_p
# Currently, Z-order (also called N-order or Morton-order) is used; Hilbert curve could also be used, but the implementation is more complex. The algorithm to convert the multi-dimensional value is called bit-interleaving. The scalar value is indexed using a B-Tree index (usually using a computed column). 

@features_1560_p
# The method can result in a drastic performance improvement over just using an index on the first column. Depending on the data and number of dimensions, the improvement is usually higher than factor 5. The tool generates a SQL query from a specified multi-dimensional range. The method used is not database dependent, and the tool can easily be ported to other databases. For an example how to use the tool, please have a look at the sample code provided in <code>TestMultiDimension.java</code>. 

@features_1561_h2
パスワードを使用する

@features_1562_h3
安全なパスワードを使用する

@features_1563_p
# Remember that weak passwords can be broken regardless of the encryption and security protocols. Don't use passwords that can be found in a dictionary. Also appending numbers does not make them secure. A way to create good passwords that can be remembered is, take the first letters of a sentence, use upper and lower case characters, and creatively include special characters. Example: 

@features_1564_code
#i'sE2rtPiUKtT

@features_1565_p
# from the sentence <code>it's easy to remember this password if you know the trick</code>. 

@features_1566_h3
パスワード: Stringの代わりにChar Arraysを使用する

@features_1567_p
# Java strings are immutable objects and cannot be safely 'destroyed' by the application. After creating a string, it will remain in the main memory of the computer at least until it is garbage collected. The garbage collection cannot be controlled by the application, and even if it is garbage collected the data may still remain in memory. It might also be possible that the part of memory containing the password is swapped to disk (because not enough main memory is available). 

@features_1568_p
# An attacker might have access to the swap file of the operating system. It is therefore a good idea to use char arrays instead of strings to store passwords. Char arrays can be cleared (filled with zeros) after use, and therefore the password will not be stored in the swap file. 

@features_1569_p
# This database supports using char arrays instead of string to pass user and file passwords. The following code can be used to do that: 

@features_1570_p
# This example requires Java 1.6. When using Swing, use <code>javax.swing.JPasswordField</code>. 

@features_1571_h3
ユーザー名 と (または) パスワードをURLで認証する

@features_1572_p
# Instead of passing the user name as a separate parameter as in <code> Connection conn = DriverManager. getConnection("jdbc:h2:~/test", "sa", "123"); </code> the user name (and/or password) can be supplied in the URL itself: <code> Connection conn = DriverManager. getConnection("jdbc:h2:~/test;USER=sa;PASSWORD=123"); </code> The settings in the URL override the settings passed as a separate parameter. 

@features_1573_h2
ユーザー定義の関数とストアドプロシージャ

@features_1574_p
# In addition to the built-in functions, this database supports user-defined Java functions. In this database, Java functions can be used as stored procedures as well. A function must be declared (registered) before it can be used. A function can be defined using source code, or as a reference to a compiled class that is available in the classpath. By default, the function aliases are stored in the current schema. 

@features_1575_h3
#Referencing a Compiled Method

@features_1576_p
# When referencing a method, the class must already be compiled and included in the classpath where the database is running. Only static Java methods are supported; both the class and the method must be public. Example Java class: 

@features_1577_p
# The Java function must be registered in the database by calling <code>CREATE ALIAS ... FOR</code>: 

@features_1578_p
# For a complete sample application, see <code>src/test/org/h2/samples/Function.java</code>. 

@features_1579_h3
#Declaring Functions as Source Code

@features_1580_p
# When defining a function alias with source code, the database tries to compile the source code using the Sun Java compiler (the class <code>com.sun.tools.javac.Main</code>) if the <code>tools.jar</code> is in the classpath. If not, <code>javac</code> is run as a separate process. Only the source code is stored in the database; the class is compiled each time the database is re-opened. Source code is usually passed as dollar quoted text to avoid escaping problems, however single quotes can be used as well. Example: 

@features_1581_p
# The method name (<code>nextPrime</code> in the example above) is ignored. By default, the three packages <code>java.util, java.math, java.sql</code> are imported. If different import statements are required, they must be declared at the beginning and separated with the tag <code>@CODE</code>: 

@features_1582_p
# The following template is used to create a complete Java class: 

@features_1583_h3
データタイプマッピング関数

@features_1584_p
# Functions that accept non-nullable parameters such as <code>int</code> will not be called if one of those parameters is <code>NULL</code>. Instead, the result of the function is <code>NULL</code>. If the function should be called if a parameter is <code>NULL</code>, you need to use <code>java.lang.Integer</code> instead. 

@features_1585_p
# SQL types are mapped to Java classes and vice-versa as in the JDBC API. For details, see <a href="datatypes.html">Data Types</a>. There are two special cases: <code>java.lang.Object</code> is mapped to <code>OTHER</code> (a serialized object). Therefore, <code>java.lang.Object</code> can not be used to match all SQL types (matching all SQL types is not supported). The second special case is <code>Object[]</code>: arrays of any class are mapped to <code>ARRAY</code>. 

@features_1586_h3
#Functions That Require a Connection

@features_1587_p
# If the first parameter of a Java function is a <code>java.sql.Connection</code>, then the connection to database is provided. This connection does not need to be closed before returning. When calling the method from within the SQL statement, this connection parameter does not need to be (can not be) specified. 

@features_1588_h3
#Functions Throwing an Exception

@features_1589_p
# If a function throws an exception, then the current statement is rolled back and the exception is thrown to the application. SQLException are directly re-thrown to the calling application; all other exceptions are first converted to a SQLException. 

@features_1590_h3
#Functions Returning a Result Set

@features_1591_p
# Functions may returns a result set. Such a function can be called with the <code>CALL</code> statement: 

@features_1592_h3
SimpleResultSetを使用する

@features_1593_p
# A function can create a result set using the <code>SimpleResultSet</code> tool: 

@features_1594_h3
関数をテーブルとして使用する

@features_1595_p
# A function that returns a result set can be used like a table. However, in this case the function is called at least twice: first while parsing the statement to collect the column names (with parameters set to <code>null</code> where not known at compile time). And then, while executing the statement to get the data (maybe multiple times if this is a join). If the function is called just to get the column list, the URL of the connection passed to the function is <code>jdbc:columnlist:connection</code>. Otherwise, the URL of the connection is <code>jdbc:default:connection</code>. 

@features_1596_h2
トリガー

@features_1597_p
# This database supports Java triggers that are called before or after a row is updated, inserted or deleted. Triggers can be used for complex consistency checks, or to update related data in the database. It is also possible to use triggers to simulate materialized views. For a complete sample application, see <code>src/test/org/h2/samples/TriggerSample.java</code>. A Java trigger must implement the interface <code>org.h2.api.Trigger</code>. The trigger class must be available in the classpath of the database engine (when using the server mode, it must be in the classpath of the server). 

@features_1598_p
# The connection can be used to query or update data in other tables. The trigger then needs to be defined in the database: 

@features_1599_p
# The trigger can be used to veto a change by throwing a <code>SQLException</code>. 

@features_1600_h2
データベースをコンパクトにする

@features_1601_p
# Empty space in the database file re-used automatically. When closing the database, the database is automatically compacted for up to 1 second by default. To compact more, use the SQL statement SHUTDOWN COMPACT. However re-creating the database may further reduce the database size because this will re-build the indexes. Here is a sample function to do this: 

@features_1602_p
# See also the sample application <code>org.h2.samples.Compact</code>. The commands <code>SCRIPT / RUNSCRIPT</code> can be used as well to create a backup of a database and re-build the database from the script. 

@features_1603_h2
キャッシュの設定

@features_1604_p
# The database keeps most frequently used data in the main memory. The amount of memory used for caching can be changed using the setting <code>CACHE_SIZE</code>. This setting can be set in the database connection URL (<code>jdbc:h2:~/test;CACHE_SIZE=131072</code>), or it can be changed at runtime using <code>SET CACHE_SIZE size</code>. The size of the cache, as represented by <code>CACHE_SIZE</code> is measured in KB, with each KB being 1024 bytes. This setting has no effect for in-memory databases. 

@features_1605_p
# Also included is an experimental second level soft reference cache. Rows in this cache are only garbage collected on low memory. By default the second level cache is disabled. To enable it, use the prefix <code>SOFT_</code>. Example: <code>jdbc:h2:~/test;CACHE_TYPE=SOFT_LRU</code>. The cache might not actually improve performance. If you plan to use it, please run your own test cases first. 

@features_1606_p
# To get information about page reads and writes, and the current caching algorithm in use, call <code>SELECT * FROM INFORMATION_SCHEMA.SETTINGS</code>. The number of pages read / written is listed. 

@fragments_1000_b
#Search:

@fragments_1001_td
#Highlight keyword(s)

@fragments_1002_a
ホーム

@fragments_1003_a
ダウンロード

@fragments_1004_a
#Cheat Sheet

@fragments_1005_b
ドキュメント

@fragments_1006_a
クイックスタート

@fragments_1007_a
インストール

@fragments_1008_a
チュートリアル

@fragments_1009_a
特徴

@fragments_1010_a
パフォーマンス

@fragments_1011_a
#Advanced

@fragments_1012_b
#Reference

@fragments_1013_a
#SQL Grammar

@fragments_1014_a
#Functions

@fragments_1015_a
データ型

@fragments_1016_a
#Javadoc

@fragments_1017_a
#PDF (1 MB)

@fragments_1018_b
サポート

@fragments_1019_a
#FAQ

@fragments_1020_a
#Error Analyzer

@fragments_1021_a
#Google Group (English)

@fragments_1022_a
#Google Group (Japanese)

@fragments_1023_a
#Google Group (Chinese)

@fragments_1024_b
#Appendix

@fragments_1025_a
#JaQu

@fragments_1026_a
ビルド

@fragments_1027_a
#History &amp; Roadmap

@fragments_1028_a
#Links

@fragments_1029_a
ライセンス

@fragments_1030_td
&nbsp;

@frame_1000_h1
H2 データベース エンジン

@frame_1001_p
# Welcome to H2, the free SQL database. The main feature of H2 are: 

@frame_1002_li
#It is free to use for everybody, source code is included 

@frame_1003_li
#Written in Java, but also available as native executable 

@frame_1004_li
#JDBC and (partial) ODBC API 

@frame_1005_li
#Embedded and client/server modes 

@frame_1006_li
#Clustering is supported 

@frame_1007_li
#A web client is included 

@frame_1008_h2
#No Javascript

@frame_1009_p
# If you are not automatically redirected to the main page, then Javascript is currently disabled or your browser does not support Javascript. Some features (for example the integrated search) require Javascript. 

@frame_1010_p
# Please enable Javascript, or go ahead without it: <a href="main.html" style="font-size: 16px; font-weight: bold">H2 Database Engine</a> 

@history_1000_h1
歴史とロードマップ

@history_1001_a
# Change Log

@history_1002_a
# Roadmap

@history_1003_a
# History of this Database Engine

@history_1004_a
# Why Java

@history_1005_a
# Supporters

@history_1006_h2
変更履歴

@history_1007_p
# The up-to-date change log is available at <a href="http://www.h2database.com/html/changelog.html"> http://www.h2database.com/html/changelog.html </a> 

@history_1008_h2
ロードマップ

@history_1009_p
# The current roadmap is available at <a href="http://www.h2database.com/html/roadmap.html"> http://www.h2database.com/html/roadmap.html </a> 

@history_1010_h2
このデータベースエンジンの歴史

@history_1011_p
# The development of H2 was started in May 2004, but it was first published on December 14th 2005. The main author of H2, Thomas Mueller, is also the original developer of Hypersonic SQL. In 2001, he joined PointBase Inc. where he wrote PointBase Micro, a commercial Java SQL database. At that point, he had to discontinue Hypersonic SQL. The HSQLDB Group was formed to continued to work on the Hypersonic SQL codebase. The name H2 stands for Hypersonic 2, however H2 does not share code with Hypersonic SQL or HSQLDB. H2 is built from scratch. 

@history_1012_h2
なぜJavaなのか

@history_1013_p
# The main reasons to use a Java database are: 

@history_1014_li
#Very simple to integrate in Java applications 

@history_1015_li
#Support for many different platforms 

@history_1016_li
#More secure than native applications (no buffer overflows) 

@history_1017_li
#User defined functions (or triggers) run very fast 

@history_1018_li
#Unicode support 

@history_1019_p
# Some think Java is too slow for low level operations, but this is no longer true. Garbage collection for example is now faster than manual memory management. 

@history_1020_p
# Developing Java code is faster than developing C or C++ code. When using Java, most time can be spent on improving the algorithms instead of porting the code to different platforms or doing memory management. Features such as Unicode and network libraries are already built-in. In Java, writing secure code is easier because buffer overflows can not occur. Features such as reflection can be used for randomized testing. 

@history_1021_p
# Java is future proof: a lot of companies support Java. Java is now open source. 

@history_1022_p
# To increase the portability and ease of use, this software depends on very few libraries. Features that are not available in open source Java implementations (such as Swing) are not used, or only used for optional features. 

@history_1023_h2
支援者

@history_1024_p
# Many thanks for those who reported bugs, gave valuable feedback, spread the word, and translated this project. Also many thanks to the donors who contributed via PayPal: 

@history_1025_a
#Code 42 Software, Inc., Minneapolis

@history_1026_a
#NetSuxxess GmbH, Germany

@history_1027_a
#Poker Copilot, Steve McLeod, Germany

@history_1028_a
#SkyCash, Poland

@history_1029_a
#Lumber-mill, Inc., Japan

@history_1030_li
#Martin Wildam, Austria 

@history_1031_li
#Donald Bleyl, USA 

@history_1032_li
#Frank Berger, Germany 

@history_1033_li
#Ashwin Jayaprakash, USA 

@history_1034_li
#Florent Ramiere, France 

@history_1035_li
#Jun Iyama, Japan 

@history_1036_li
#Antonio Casqueiro, Portugal 

@history_1037_li
#Oliver Computing LLC, USA 

@history_1038_li
#Harpal Grover Consulting Inc., USA 

@history_1039_li
#Elisabetta Berlini, Italy 

@history_1040_li
#William Gilbert, USA 

@history_1041_li
#Antonio Dieguez Rojas, Chile 

@history_1042_a
#Ontology Works, USA

@history_1043_li
#Pete Haidinyak, USA 

@history_1044_li
#William Osmond, USA 

@history_1045_li
#Joachim Ansorg, Germany 

@history_1046_li
#Oliver Soerensen, Germany 

@history_1047_li
#Christos Vasilakis, Greece 

@history_1048_li
#Fyodor Kupolov, Denmark 

@history_1049_li
#Jakob Jenkov, Denmark 

@history_1050_li
#St&eacute;phane Chartrand, Switzerland 

@history_1051_li
#Glenn Kidd, USA 

@history_1052_li
#Gustav Trede, Sweden 

@history_1053_li
#Joonas Pulakka, Finland 

@history_1054_li
#Bjorn Darri Sigurdsson, Iceland 

@history_1055_li
#Iyama Jun, Japan 

@history_1056_li
#Gray Watson, USA 

@history_1057_li
#Erik Dick, Germany 

@installation_1000_h1
インストール

@installation_1001_a
# Requirements

@installation_1002_a
# Supported Platforms

@installation_1003_a
# Installing the Software

@installation_1004_a
# Directory Structure

@installation_1005_h2
必要条件

@installation_1006_p
# To run the database, the following minimum software stack is known to work: 

@installation_1007_li
#Windows XP or Vista, Mac OS X, or Linux 

@installation_1008_li
#Recommended Windows file system: NTFS (FAT32 only supports files up to 4 GB) 

@installation_1009_li
#Sun JDK 1.5 or newer 

@installation_1010_li
#Mozilla Firefox 

@installation_1011_h2
サポートされているプラットフォーム

@installation_1012_p
# As this database is written in Java, it can run on many different platforms. It is tested with Java 1.5 and 1.6 but can also be compiled to native code using GCJ. The source code does not use features of Java 1.6. Currently, the database is developed and tested on Windows XP and Mac OS X using the Sun JDK 1.5, but it also works in many other operating systems and using other Java runtime environments. 

@installation_1013_h2
ソフトウェアのインストール

@installation_1014_p
# To install the software, run the installer or unzip it to a directory of your choice. 

@installation_1015_h2
ディレクトリ構成

@installation_1016_p
# After installing, you should get the following directory structure: 

@installation_1017_th
ディレクトリ

@installation_1018_th
コンテンツ

@installation_1019_td
bin

@installation_1020_td
JARとbatchファイル

@installation_1021_td
docs

@installation_1022_td
ドキュメント

@installation_1023_td
docs/html

@installation_1024_td
HTMLページ

@installation_1025_td
docs/javadoc

@installation_1026_td
Javadocファイル

@installation_1027_td
#ext

@installation_1028_td
#External dependencies (downloaded when building)

@installation_1029_td
service

@installation_1030_td
Windows Serviceとしてデータベースを実行するツール

@installation_1031_td
src

@installation_1032_td
Sourceファイル

@installation_1033_td
#src/docsrc

@installation_1034_td
#Documentation sources

@installation_1035_td
#src/installer

@installation_1036_td
#Installer, shell, and release build script

@installation_1037_td
#src/main

@installation_1038_td
#Database engine source code

@installation_1039_td
#src/test

@installation_1040_td
#Test source code

@installation_1041_td
#src/tools

@installation_1042_td
#Tools and database adapters source code

@jaqu_1000_h1
#JaQu

@jaqu_1001_a
# What is JaQu

@jaqu_1002_a
# Differences to Other Data Access Tools

@jaqu_1003_a
# Current State

@jaqu_1004_a
# Building the JaQu Library

@jaqu_1005_a
# Requirements

@jaqu_1006_a
# Example Code

@jaqu_1007_a
# Configuration

@jaqu_1008_a
# Natural Syntax

@jaqu_1009_a
# Other Ideas

@jaqu_1010_a
# Similar Projects

@jaqu_1011_h2
#What is JaQu

@jaqu_1012_p
# JaQu stands for Java Query and allows to access databases using pure Java. JaQu provides a fluent interface (or internal DSL) to access a database. JaQu is something like LINQ for Java (LINQ stands for "language integrated query" and is a Microsoft .NET technology). The following JaQu code: 

@jaqu_1013_p
# stands for the SQL statement: 

@jaqu_1014_h2
#Differences to Other Data Access Tools

@jaqu_1015_p
# Unlike SQL, JaQu can be easily integrated in Java applications. Because JaQu is pure Java, auto-complete in the IDE and Javadoc and are supported. Type checking is performed by the compiler. JaQu fully protects against SQL injection. 

@jaqu_1016_p
# JaQu is more a replacement for JDBC than it is a replacement for tools like Hibernate. With JaQu, you don't write SQL statements as Strings. JaQu is much smaller and simpler than other persistence frameworks such as Hibernate, but it also does not provide all the features of those. Unlike iBatis and Hibernate, no XML or annotation based configuration is required; instead the configuration (if required at all) is done in pure Java, in the application itself. 

@jaqu_1017_p
# JaQu does not require or contain any data caching mechanism. Like JDBC and iBatis, JaQu provides full control over when and what SQL statements are executed (but without having to write SQL statements as Strings). 

@jaqu_1018_h3
#Restrictions

@jaqu_1019_p
# Primitive types (eg. <code>boolean, int, long, double</code>) are not supported. Use <code>java.lang.Boolean, Integer, Long, Double</code> instead. 

@jaqu_1020_h3
#Why in Java?

@jaqu_1021_p
# Most people use Java in their application. Mixing Java and another language (for example Scala or Groovy) in the same application is complicated: you would need to split the application and database code. 

@jaqu_1022_h2
#Current State

@jaqu_1023_p
# Currently, JaQu is only tested with the H2 database. The API may change in future versions. JaQu is not part of the h2 jar file, however the source code is included in H2, under: 

@jaqu_1024_code
#src/test/org/h2/test/jaqu/*

@jaqu_1025_li
# (samples and tests) 

@jaqu_1026_code
#src/tools/org/h2/jaqu/*

@jaqu_1027_li
# (framework) 

@jaqu_1028_h2
#Building the JaQu Library

@jaqu_1029_p
# To create the JaQu jar file, run: <code>build jarJaqu</code>. This will create the file <code>bin/h2jaqu.jar</code>. 

@jaqu_1030_h2
必要条件

@jaqu_1031_p
# JaQu requires Java 1.5. Annotations are not need. Currently, JaQu is only tested with the H2 database engine, however in theory it should work with any database that supports the JDBC API. 

@jaqu_1032_h2
#Example Code

@jaqu_1033_h2
#Configuration

@jaqu_1034_p
# JaQu does not require any configuration when using the default mapping. To define table indices, or if you want to map a class to a table with a different name, or a field to a column with another name, create a function called <code>define</code> in the data class. Example: 

@jaqu_1035_p
# The method <code>define()</code> contains the mapping definition. It is called once when the class is used for the first time. Like annotations, the mapping is defined in the class itself. Unlike when using annotations, the compiler can check the syntax even for multi-column objects (multi-column indexes, multi-column primary keys and so on). Because the definition is written in regular Java, the configuration can depend on the environment. This is not possible using annotations. Unlike XML mapping configuration, the configuration is integrated in the class itself. 

@jaqu_1036_h2
#Natural Syntax

@jaqu_1037_p
#The plan is to support more natural (pure Java) syntax in conditions. To do that, the condition class is de-compiled to a SQL condition. A proof of concept decompiler is included (but it doesn't work yet). The planned syntax is: 

@jaqu_1038_h2
#Other Ideas

@jaqu_1039_p
# This project has just been started, and nothing is fixed yet. Some ideas for what to implement are: 

@jaqu_1040_li
#Support queries on collections (instead of using a database). 

@jaqu_1041_li
#Provide API level compatibility with JPA (so that JaQu can be used as an extension of JPA). 

@jaqu_1042_li
#Internally use a JPA implementation (for example Hibernate) instead of SQL directly. 

@jaqu_1043_li
#Use PreparedStatements and cache them. 

@jaqu_1044_h2
#Similar Projects

@jaqu_1045_a
#Cement Framework

@jaqu_1046_a
#Dreamsource ORM

@jaqu_1047_a
#Empire-db

@jaqu_1048_a
#JEQUEL: Java Embedded QUEry Language

@jaqu_1049_a
#Joist

@jaqu_1050_a
#JoSQL

@jaqu_1051_a
#LIQUidFORM

@jaqu_1052_a
#Quaere (Alias implementation)

@jaqu_1053_a
#Quaere

@jaqu_1054_a
#Querydsl

@jaqu_1055_a
#Squill

@license_1000_h1
ライセンス

@license_1001_h2
#Summary and License FAQ

@license_1002_p
# H2 is dual licensed and available under a modified version of the MPL 1.1 (<a href="http://www.mozilla.org/MPL">Mozilla Public License</a>) or under the (unmodified) EPL 1.0 (<a href="http://opensource.org/licenses/eclipse-1.0.php">Eclipse Public License</a>). The changes to the MPL are 

@license_1003_em
#underlined</em>. There is a License FAQ for both the MPL and the EPL, most of that is applicable to the H2 License as well. 

@license_1004_li
#You can use H2 for free. You can integrate it into your application (including commercial applications), and you can distribute it. 

@license_1005_li
#Files containing only your code are not covered by this license (it is 'commercial friendly'). 

@license_1006_li
#Modifications to the H2 source code must be published. 

@license_1007_li
#You don't need to provide the source code of H2 if you did not modify anything. 

@license_1008_p
# However, nobody is allowed to rename H2, modify it a little, and sell it as a database engine without telling the customers it is in fact H2. This happened to HSQLDB: a company called 'bungisoft' copied HSQLDB, renamed it to 'RedBase', and tried to sell it, hiding the fact that it was in fact just HSQLDB. It seems 'bungisoft' does not exist any more, but you can use the <a href="http://www.archive.org">Wayback Machine</a> and visit old web pages of <code>http://www.bungisoft.com</code>. 

@license_1009_p
# About porting the source code to another language (for example C# or C++): converted source code (even if done manually) stays under the same copyright and license as the original code. The copyright of the ported source code does not (automatically) go to the person who ported the code. 

@license_1010_h2
#H2 License, Version 1.0

@license_1011_h3
#1. Definitions

@license_1012_b
#1.0.1. "Commercial Use"

@license_1013_p
# means distribution or otherwise making the Covered Code available to a third party. 

@license_1014_b
#1.1. "Contributor"

@license_1015_p
# means each entity that creates or contributes to the creation of Modifications. 

@license_1016_b
#1.2. "Contributor Version"

@license_1017_p
# means the combination of the Original Code, prior Modifications used by a Contributor, and the Modifications made by that particular Contributor. 

@license_1018_b
#1.3. "Covered Code"

@license_1019_p
# means the Original Code or Modifications or the combination of the Original Code and Modifications, in each case including portions thereof. 

@license_1020_b
#1.4. "Electronic Distribution Mechanism"

@license_1021_p
# means a mechanism generally accepted in the software development community for the electronic transfer of data. 

@license_1022_b
#1.5. "Executable"

@license_1023_p
# means Covered Code in any form other than Source Code. 

@license_1024_b
#1.6. "Initial Developer"

@license_1025_p
# means the individual or entity identified as the Initial Developer in the Source Code notice required by <a href="#exhibit-a">Exhibit A</a>. 

@license_1026_b
#1.7. "Larger Work"

@license_1027_p
# means a work which combines Covered Code or portions thereof with code not governed by the terms of this License. 

@license_1028_b
#1.8. "License"

@license_1029_p
# means this document. 

@license_1030_b
#1.8.1. "Licensable"

@license_1031_p
# means having the right to grant, to the maximum extent possible, whether at the time of the initial grant or subsequently acquired, any and all of the rights conveyed herein. 

@license_1032_b
#1.9. "Modifications"

@license_1033_p
# means any addition to or deletion from the substance or structure of either the Original Code or any previous Modifications. When Covered Code is released as a series of files, a Modification is: 

@license_1034_p
#1.9.a. Any addition to or deletion from the contents of a file containing Original Code or previous Modifications. 

@license_1035_p
#1.9.b. Any new file that contains any part of the Original Code or previous Modifications. 

@license_1036_b
#1.10. "Original Code"

@license_1037_p
# means Source Code of computer software code which is described in the Source Code notice required by <a href="#exhibit-a">Exhibit A</a> as Original Code, and which, at the time of its release under this License is not already Covered Code governed by this License. 

@license_1038_b
#1.10.1. "Patent Claims"

@license_1039_p
# means any patent claim(s), now owned or hereafter acquired, including without limitation, method, process, and apparatus claims, in any patent Licensable by grantor. 

@license_1040_b
#1.11. "Source Code"

@license_1041_p
# means the preferred form of the Covered Code for making modifications to it, including all modules it contains, plus any associated interface definition files, scripts used to control compilation and installation of an Executable, or source code differential comparisons against either the Original Code or another well known, available Covered Code of the Contributor's choice. The Source Code can be in a compressed or archival form, provided the appropriate decompression or de-archiving software is widely available for no charge. 

@license_1042_b
#1.12. "You" (or "Your")

@license_1043_p
# means an individual or a legal entity exercising rights under, and complying with all of the terms of, this License or a future version of this License issued under <a href="#section-6.1">Section 6.1.</a> For legal entities, "You" includes any entity which controls, is controlled by, or is under common control with You. For purposes of this definition, "control" means (a) the power, direct or indirect, to cause the direction or management of such entity, whether by contract or otherwise, or (b) ownership of more than fifty percent (50%) of the outstanding shares or beneficial ownership of such entity. 

@license_1044_h3
#2. Source Code License

@license_1045_h4
#2.1. The Initial Developer Grant

@license_1046_p
# The Initial Developer hereby grants You a world-wide, royalty-free, non-exclusive license, subject to third party intellectual property claims: 

@license_1047_p
#2.1.a. under intellectual property rights (other than patent or trademark) Licensable by Initial Developer to use, reproduce, modify, display, perform, sublicense and distribute the Original Code (or portions thereof) with or without Modifications, and/or as part of a Larger Work; and 

@license_1048_p
#2.1.b. under Patents Claims infringed by the making, using or selling of Original Code, to make, have made, use, practice, sell, and offer for sale, and/or otherwise dispose of the Original Code (or portions thereof). 

@license_1049_p
#2.1.c. the licenses granted in this Section 2.1 (<a href="#section-2.1-a">a</a>) and (<a href="#section-2.1-b">b</a>) are effective on the date Initial Developer first distributes Original Code under the terms of this License. 

@license_1050_p
#2.1.d. Notwithstanding Section 2.1 (<a href="#section-2.1-b">b</a>) above, no patent license is granted: 1) for code that You delete from the Original Code; 2) separate from the Original Code; or 3) for infringements caused by: i) the modification of the Original Code or ii) the combination of the Original Code with other software or devices. 

@license_1051_h4
#2.2. Contributor Grant

@license_1052_p
# Subject to third party intellectual property claims, each Contributor hereby grants You a world-wide, royalty-free, non-exclusive license 

@license_1053_p
#2.2.a. under intellectual property rights (other than patent or trademark) Licensable by Contributor, to use, reproduce, modify, display, perform, sublicense and distribute the Modifications created by such Contributor (or portions thereof) either on an unmodified basis, with other Modifications, as Covered Code and/or as part of a Larger Work; and 

@license_1054_p
#2.2.b. under Patent Claims infringed by the making, using, or selling of Modifications made by that Contributor either alone and/or in combination with its Contributor Version (or portions of such combination), to make, use, sell, offer for sale, have made, and/or otherwise dispose of: 1) Modifications made by that Contributor (or portions thereof); and 2) the combination of Modifications made by that Contributor with its Contributor Version (or portions of such combination). 

@license_1055_p
#2.2.c. the licenses granted in Sections 2.2 (<a href="#section-2.2-a">a</a>) and 2.2 (<a href="#section-2.2-b">b</a>) are effective on the date Contributor first makes Commercial Use of the Covered Code. 

@license_1056_p
#2.2.c. Notwithstanding Section 2.2 (<a href="#section-2.2-b">b</a>) above, no patent license is granted: 1) for any code that Contributor has deleted from the Contributor Version; 2) separate from the Contributor Version; 3) for infringements caused by: i) third party modifications of Contributor Version or ii) the combination of Modifications made by that Contributor with other software (except as part of the Contributor Version) or other devices; or 4) under Patent Claims infringed by Covered Code in the absence of Modifications made by that Contributor. 

@license_1057_h3
#3. Distribution Obligations

@license_1058_h4
#3.1. Application of License

@license_1059_p
# The Modifications which You create or to which You contribute are governed by the terms of this License, including without limitation Section <a href="#section-2.2">2.2</a>. The Source Code version of Covered Code may be distributed only under the terms of this License or a future version of this License released under Section <a href="#section-6.1">6.1</a>, and You must include a copy of this License with every copy of the Source Code You distribute. You may not offer or impose any terms on any Source Code version that alters or restricts the applicable version of this License or the recipients' rights hereunder. However, You may include an additional document offering the additional rights described in Section <a href="#section-3.5">3.5</a>. 

@license_1060_h4
#3.2. Availability of Source Code

@license_1061_p
# Any Modification which You create or to which You contribute must be made available in Source Code form under the terms of this License either on the same media as an Executable version or via an accepted Electronic Distribution Mechanism to anyone to whom you made an Executable version available; and if made available via Electronic Distribution Mechanism, must remain available for at least twelve (12) months after the date it initially became available, or at least six (6) months after a subsequent version of that particular Modification has been made available to such recipients. You are responsible for ensuring that the Source Code version remains available even if the Electronic Distribution Mechanism is maintained by a third party. 

@license_1062_h4
#3.3. Description of Modifications

@license_1063_p
# You must cause all Covered Code to which You contribute to contain a file documenting the changes You made to create that Covered Code and the date of any change. You must include a prominent statement that the Modification is derived, directly or indirectly, from Original Code provided by the Initial Developer and including the name of the Initial Developer in (a) the Source Code, and (b) in any notice in an Executable version or related documentation in which You describe the origin or ownership of the Covered Code. 

@license_1064_h4
#3.4. Intellectual Property Matters

@license_1065_b
#3.4.a. Third Party Claims:

@license_1066_p
# If Contributor has knowledge that a license under a third party's intellectual property rights is required to exercise the rights granted by such Contributor under Sections <a href="#section-2.1">2.1</a> or <a href="#section-2.2">2.2</a>, Contributor must include a text file with the Source Code distribution titled "LEGAL" which describes the claim and the party making the claim in sufficient detail that a recipient will know whom to contact. If Contributor obtains such knowledge after the Modification is made available as described in Section <a href="#section-3.2">3.2</a>, Contributor shall promptly modify the LEGAL file in all copies Contributor makes available thereafter and shall take other steps (such as notifying appropriate mailing lists or newsgroups) reasonably calculated to inform those who received the Covered Code that new knowledge has been obtained. 

@license_1067_b
#3.4.b. Contributor APIs:

@license_1068_p
# If Contributor's Modifications include an application programming interface and Contributor has knowledge of patent licenses which are reasonably necessary to implement that API, Contributor must also include this information in the legal file. 

@license_1069_b
#3.4.c. Representations:

@license_1070_p
# Contributor represents that, except as disclosed pursuant to Section 3.4 (<a href="#section-3.4-a">a</a>) above, Contributor believes that Contributor's Modifications are Contributor's original creation(s) and/or Contributor has sufficient rights to grant the rights conveyed by this License. 

@license_1071_h4
#3.5. Required Notices

@license_1072_p
# You must duplicate the notice in <a href="#exhibit-a">Exhibit A</a> in each file of the Source Code. If it is not possible to put such notice in a particular Source Code file due to its structure, then You must include such notice in a location (such as a relevant directory) where a user would be likely to look for such a notice. If You created one or more Modification(s) You may add your name as a Contributor to the notice described in <a href="#exhibit-a">Exhibit A</a>. You must also duplicate this License in any documentation for the Source Code where You describe recipients' rights or ownership rights relating to Covered Code. You may choose to offer, and to charge a fee for, warranty, support, indemnity or liability obligations to one or more recipients of Covered Code. However, You may do so only on Your own behalf, and not on behalf of the Initial Developer or any Contributor. You must make it absolutely clear than any such warranty, support, indemnity or liability obligation is offered by You alone, and You hereby agree to indemnify the Initial Developer and every Contributor for any liability incurred by the Initial Developer or such Contributor as a result of warranty, support, indemnity or liability terms You offer. 

@license_1073_h4
#3.6. Distribution of Executable Versions

@license_1074_p
# You may distribute Covered Code in Executable form only if the requirements of Sections <a href="#section-3.1">3.1</a>, <a href="#section-3.2">3.2</a>, <a href="#section-3.3">3.3</a>, <a href="#section-3.4">3.4</a> and <a href="#section-3.5">3.5</a> have been met for that Covered Code, and if You include a notice stating that the Source Code version of the Covered Code is available under the terms of this License, including a description of how and where You have fulfilled the obligations of Section <a href="#section-3.2">3.2</a>. The notice must be conspicuously included in any notice in an Executable version, related documentation or collateral in which You describe recipients' rights relating to the Covered Code. You may distribute the Executable version of Covered Code or ownership rights under a license of Your choice, which may contain terms different from this License, provided that You are in compliance with the terms of this License and that the license for the Executable version does not attempt to limit or alter the recipient's rights in the Source Code version from the rights set forth in this License. If You distribute the Executable version under a different license You must make it absolutely clear that any terms which differ from this License are offered by You alone, not by the Initial Developer or any Contributor. You hereby agree to indemnify the Initial Developer and every Contributor for any liability incurred by the Initial Developer or such Contributor as a result of any such terms You offer. 

@license_1075_h4
#3.7. Larger Works

@license_1076_p
# You may create a Larger Work by combining Covered Code with other code not governed by the terms of this License and distribute the Larger Work as a single product. In such a case, You must make sure the requirements of this License are fulfilled for the Covered Code. 

@license_1077_h3
#4. Inability to Comply Due to Statute or Regulation.

@license_1078_p
# If it is impossible for You to comply with any of the terms of this License with respect to some or all of the Covered Code due to statute, judicial order, or regulation then You must: (a) comply with the terms of this License to the maximum extent possible; and (b) describe the limitations and the code they affect. Such description must be included in the <b>legal</b> file described in Section <a href="#section-3.4">3.4</a> and must be included with all distributions of the Source Code. Except to the extent prohibited by statute or regulation, such description must be sufficiently detailed for a recipient of ordinary skill to be able to understand it. 

@license_1079_h3
#5. Application of this License.

@license_1080_p
# This License applies to code to which the Initial Developer has attached the notice in <a href="#exhibit-a">Exhibit A</a> and to related Covered Code. 

@license_1081_h3
#6. Versions of the License.

@license_1082_h4
#6.1. New Versions

@license_1083_p
# The 

@license_1084_em
#H2 Group</em> may publish revised and/or new versions of the License from time to time. Each version will be given a distinguishing version number. 

@license_1085_h4
#6.2. Effect of New Versions

@license_1086_p
# Once Covered Code has been published under a particular version of the License, You may always continue to use it under the terms of that version. You may also choose to use such Covered Code under the terms of any subsequent version of the License published by the 

@license_1087_em
#H2 Group</em>. No one other than the 

@license_1088_em
#H2 Group</em> has the right to modify the terms applicable to Covered Code created under this License. 

@license_1089_h4
#6.3. Derivative Works

@license_1090_p
# If You create or use a modified version of this License (which you may only do in order to apply it to code which is not already Covered Code governed by this License), You must (a) rename Your license so that the phrases 

@license_1091_em
#"H2 Group", "H2"</em> or any confusingly similar phrase do not appear in your license (except to note that your license differs from this License) and (b) otherwise make it clear that Your version of the license contains terms which differ from the 

@license_1092_em
#H2 License</em>. (Filling in the name of the Initial Developer, Original Code or Contributor in the notice described in <a href="#exhibit-a">Exhibit A</a> shall not of themselves be deemed to be modifications of this License.) 

@license_1093_h3
#7. Disclaimer of Warranty

@license_1094_p
# Covered code is provided under this license on an "as is" basis, without warranty of any kind, either expressed or implied, including, without limitation, warranties that the covered code is free of defects, merchantable, fit for a particular purpose or non-infringing. The entire risk as to the quality and performance of the covered code is with you. Should any covered code prove defective in any respect, you (not the initial developer or any other contributor) assume the cost of any necessary servicing, repair or correction. This disclaimer of warranty constitutes an essential part of this license. No use of any covered code is authorized hereunder except under this disclaimer. 

@license_1095_h3
#8. Termination

@license_1096_p
#8.1. This License and the rights granted hereunder will terminate automatically if You fail to comply with terms herein and fail to cure such breach within 30 days of becoming aware of the breach. All sublicenses to the Covered Code which are properly granted shall survive any termination of this License. Provisions which, by their nature, must remain in effect beyond the termination of this License shall survive. 

@license_1097_p
#8.2. If You initiate litigation by asserting a patent infringement claim (excluding declaratory judgment actions) against Initial Developer or a Contributor (the Initial Developer or Contributor against whom You file such action is referred to as "Participant") alleging that: 

@license_1098_p
#8.2.a. such Participant's Contributor Version directly or indirectly infringes any patent, then any and all rights granted by such Participant to You under Sections <a href="#section-2.1">2.1</a> and/or <a href="#section-2.2">2.2</a> of this License shall, upon 60 days notice from Participant terminate prospectively, unless if within 60 days after receipt of notice You either: (i) agree in writing to pay Participant a mutually agreeable reasonable royalty for Your past and future use of Modifications made by such Participant, or (ii) withdraw Your litigation claim with respect to the Contributor Version against such Participant. If within 60 days of notice, a reasonable royalty and payment arrangement are not mutually agreed upon in writing by the parties or the litigation claim is not withdrawn, the rights granted by Participant to You under Sections <a href="#section-2.1">2.1</a> and/or <a href="#section-2.2">2.2</a> automatically terminate at the expiration of the 60 day notice period specified above. 

@license_1099_p
#8.2.b. any software, hardware, or device, other than such Participant's Contributor Version, directly or indirectly infringes any patent, then any rights granted to You by such Participant under Sections 2.1(<a href="#section-2.1-b">b</a>) and 2.2(<a href="#section-2.2-b">b</a>) are revoked effective as of the date You first made, used, sold, distributed, or had made, Modifications made by that Participant. 

@license_1100_p
#8.3. If You assert a patent infringement claim against Participant alleging that such Participant's Contributor Version directly or indirectly infringes any patent where such claim is resolved (such as by license or settlement) prior to the initiation of patent infringement litigation, then the reasonable value of the licenses granted by such Participant under Sections <a href="#section-2.1">2.1</a> or <a href="#section-2.2">2.2</a> shall be taken into account in determining the amount or value of any payment or license. 

@license_1101_p
#8.4. In the event of termination under Sections <a href="#section-8.1">8.1</a> or <a href="#section-8.2">8.2</a> above, all end user license agreements (excluding distributors and resellers) which have been validly granted by You or any distributor hereunder prior to termination shall survive termination. 

@license_1102_h3
#9. Limitation of Liability

@license_1103_p
# Under no circumstances and under no legal theory, whether tort (including negligence), contract, or otherwise, shall you, the initial developer, any other contributor, or any distributor of covered code, or any supplier of any of such parties, be liable to any person for any indirect, special, incidental, or consequential damages of any character including, without limitation, damages for loss of goodwill, work stoppage, computer failure or malfunction, or any and all other commercial damages or losses, even if such party shall have been informed of the possibility of such damages. This limitation of liability shall not apply to liability for death or personal injury resulting from such party's negligence to the extent applicable law prohibits such limitation. Some jurisdictions do not allow the exclusion or limitation of incidental or consequential damages, so this exclusion and limitation may not apply to you. 

@license_1104_h3
#10. United States Government End Users

@license_1105_p
# The Covered Code is a "commercial item", as that term is defined in 48 C.F.R. 2.101 (October 1995), consisting of "commercial computer software" and "commercial computer software documentation", as such terms are used in 48 C.F.R. 12.212 (September 1995). Consistent with 48 C.F.R. 12.212 and 48 C.F.R. 227.7202-1 through 227.7202-4 (June 1995), all U.S. Government End Users acquire Covered Code with only those rights set forth herein. 

@license_1106_h3
#11. Miscellaneous

@license_1107_p
# This License represents the complete agreement concerning subject matter hereof. If any provision of this License is held to be unenforceable, such provision shall be reformed only to the extent necessary to make it enforceable. This License shall be governed by California law provisions (except to the extent applicable law, if any, provides otherwise), excluding its conflict-of-law provisions. With respect to disputes in which at least one party is a citizen of, or an entity chartered or registered to do business in United States of America, any litigation relating to this License shall be subject to the jurisdiction of the Federal Courts of the Northern District of California, with venue lying in Santa Clara County, California, with the losing party responsible for costs, including without limitation, court costs and reasonable attorneys' fees and expenses. The application of the United Nations Convention on Contracts for the International Sale of Goods is expressly excluded. Any law or regulation which provides that the language of a contract shall be construed against the drafter shall not apply to this License. 

@license_1108_h3
#12. Responsibility for Claims

@license_1109_p
# As between Initial Developer and the Contributors, each party is responsible for claims and damages arising, directly or indirectly, out of its utilization of rights under this License and You agree to work with Initial Developer and Contributors to distribute such responsibility on an equitable basis. Nothing herein is intended or shall be deemed to constitute any admission of liability. 

@license_1110_h3
#13. Multiple-Licensed Code

@license_1111_p
# Initial Developer may designate portions of the Covered Code as "Multiple-Licensed". "Multiple-Licensed" means that the Initial Developer permits you to utilize portions of the Covered Code under Your choice of this or the alternative licenses, if any, specified by the Initial Developer in the file described in <a href="#exhibit-a">Exhibit A</a>. 

@license_1112_h3
#Exhibit A

@license_1113_h2
#Eclipse Public License - Version 1.0

@license_1114_p
# THE ACCOMPANYING PROGRAM IS PROVIDED UNDER THE TERMS OF THIS ECLIPSE PUBLIC LICENSE ("AGREEMENT"). ANY USE, REPRODUCTION OR DISTRIBUTION OF THE PROGRAM CONSTITUTES RECIPIENT'S ACCEPTANCE OF THIS AGREEMENT. 

@license_1115_h3
#1. DEFINITIONS

@license_1116_p
# "Contribution" means: 

@license_1117_p
# a) in the case of the initial Contributor, the initial code and documentation distributed under this Agreement, and 

@license_1118_p
# b) in the case of each subsequent Contributor: 

@license_1119_p
# i) changes to the Program, and 

@license_1120_p
# ii) additions to the Program; 

@license_1121_p
# where such changes and/or additions to the Program originate from and are distributed by that particular Contributor. A Contribution 'originates' from a Contributor if it was added to the Program by such Contributor itself or anyone acting on such Contributor's behalf. Contributions do not include additions to the Program which: (i) are separate modules of software distributed in conjunction with the Program under their own license agreement, and (ii) are not derivative works of the Program. 

@license_1122_p
# "Contributor" means any person or entity that distributes the Program. 

@license_1123_p
# "Licensed Patents " mean patent claims licensable by a Contributor which are necessarily infringed by the use or sale of its Contribution alone or when combined with the Program. 

@license_1124_p
# "Program" means the Contributions distributed in accordance with this Agreement. 

@license_1125_p
# "Recipient" means anyone who receives the Program under this Agreement, including all Contributors. 

@license_1126_h3
#2. GRANT OF RIGHTS

@license_1127_p
# a) Subject to the terms of this Agreement, each Contributor hereby grants Recipient a non-exclusive, worldwide, royalty-free copyright license to reproduce, prepare derivative works of, publicly display, publicly perform, distribute and sublicense the Contribution of such Contributor, if any, and such derivative works, in source code and object code form. 

@license_1128_p
# b) Subject to the terms of this Agreement, each Contributor hereby grants Recipient a non-exclusive, worldwide, royalty-free patent license under Licensed Patents to make, use, sell, offer to sell, import and otherwise transfer the Contribution of such Contributor, if any, in source code and object code form. This patent license shall apply to the combination of the Contribution and the Program if, at the time the Contribution is added by the Contributor, such addition of the Contribution causes such combination to be covered by the Licensed Patents. The patent license shall not apply to any other combinations which include the Contribution. No hardware per se is licensed hereunder. 

@license_1129_p
# c) Recipient understands that although each Contributor grants the licenses to its Contributions set forth herein, no assurances are provided by any Contributor that the Program does not infringe the patent or other intellectual property rights of any other entity. Each Contributor disclaims any liability to Recipient for claims brought by any other entity based on infringement of intellectual property rights or otherwise. As a condition to exercising the rights and licenses granted hereunder, each Recipient hereby assumes sole responsibility to secure any other intellectual property rights needed, if any. For example, if a third party patent license is required to allow Recipient to distribute the Program, it is Recipient's responsibility to acquire that license before distributing the Program. 

@license_1130_p
# d) Each Contributor represents that to its knowledge it has sufficient copyright rights in its Contribution, if any, to grant the copyright license set forth in this Agreement. 

@license_1131_h3
#3. REQUIREMENTS

@license_1132_p
# A Contributor may choose to distribute the Program in object code form under its own license agreement, provided that: 

@license_1133_p
# a) it complies with the terms and conditions of this Agreement; and 

@license_1134_p
# b) its license agreement: 

@license_1135_p
# i) effectively disclaims on behalf of all Contributors all warranties and conditions, express and implied, including warranties or conditions of title and non-infringement, and implied warranties or conditions of merchantability and fitness for a particular purpose; 

@license_1136_p
# ii) effectively excludes on behalf of all Contributors all liability for damages, including direct, indirect, special, incidental and consequential damages, such as lost profits; 

@license_1137_p
# iii) states that any provisions which differ from this Agreement are offered by that Contributor alone and not by any other party; and 

@license_1138_p
# iv) states that source code for the Program is available from such Contributor, and informs licensees how to obtain it in a reasonable manner on or through a medium customarily used for software exchange. 

@license_1139_p
# When the Program is made available in source code form: 

@license_1140_p
# a) it must be made available under this Agreement; and 

@license_1141_p
# b) a copy of this Agreement must be included with each copy of the Program. 

@license_1142_p
# Contributors may not remove or alter any copyright notices contained within the Program. 

@license_1143_p
# Each Contributor must identify itself as the originator of its Contribution, if any, in a manner that reasonably allows subsequent Recipients to identify the originator of the Contribution. 

@license_1144_h3
#4. COMMERCIAL DISTRIBUTION

@license_1145_p
# Commercial distributors of software may accept certain responsibilities with respect to end users, business partners and the like. While this license is intended to facilitate the commercial use of the Program, the Contributor who includes the Program in a commercial product offering should do so in a manner which does not create potential liability for other Contributors. Therefore, if a Contributor includes the Program in a commercial product offering, such Contributor ("Commercial Contributor") hereby agrees to defend and indemnify every other Contributor ("Indemnified Contributor") against any losses, damages and costs (collectively "Losses") arising from claims, lawsuits and other legal actions brought by a third party against the Indemnified Contributor to the extent caused by the acts or omissions of such Commercial Contributor in connection with its distribution of the Program in a commercial product offering. The obligations in this section do not apply to any claims or Losses relating to any actual or alleged intellectual property infringement. In order to qualify, an Indemnified Contributor must: a) promptly notify the Commercial Contributor in writing of such claim, and b) allow the Commercial Contributor to control, and cooperate with the Commercial Contributor in, the defense and any related settlement negotiations. The Indemnified Contributor may participate in any such claim at its own expense. 

@license_1146_p
# For example, a Contributor might include the Program in a commercial product offering, Product X. That Contributor is then a Commercial Contributor. If that Commercial Contributor then makes performance claims, or offers warranties related to Product X, those performance claims and warranties are such Commercial Contributor's responsibility alone. Under this section, the Commercial Contributor would have to defend claims against the other Contributors related to those performance claims and warranties, and if a court requires any other Contributor to pay any damages as a result, the Commercial Contributor must pay those damages. 

@license_1147_h3
#5. NO WARRANTY

@license_1148_p
# EXCEPT AS EXPRESSLY SET FORTH IN THIS AGREEMENT, THE PROGRAM IS PROVIDED ON AN "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED INCLUDING, WITHOUT LIMITATION, ANY WARRANTIES OR CONDITIONS OF TITLE, NON-INFRINGEMENT, MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Each Recipient is solely responsible for determining the appropriateness of using and distributing the Program and assumes all risks associated with its exercise of rights under this Agreement, including but not limited to the risks and costs of program errors, compliance with applicable laws, damage to or loss of data, programs or equipment, and unavailability or interruption of operations. 

@license_1149_h3
#6. DISCLAIMER OF LIABILITY

@license_1150_p
# EXCEPT AS EXPRESSLY SET FORTH IN THIS AGREEMENT, NEITHER RECIPIENT NOR ANY CONTRIBUTORS SHALL HAVE ANY LIABILITY FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING WITHOUT LIMITATION LOST PROFITS), HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OR DISTRIBUTION OF THE PROGRAM OR THE EXERCISE OF ANY RIGHTS GRANTED HEREUNDER, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. 

@license_1151_h3
#7. GENERAL

@license_1152_p
# If any provision of this Agreement is invalid or unenforceable under applicable law, it shall not affect the validity or enforceability of the remainder of the terms of this Agreement, and without further action by the parties hereto, such provision shall be reformed to the minimum extent necessary to make such provision valid and enforceable. 

@license_1153_p
# If Recipient institutes patent litigation against any entity (including a cross-claim or counterclaim in a lawsuit) alleging that the Program itself (excluding combinations of the Program with other software or hardware) infringes such Recipient's patent(s), then such Recipient's rights granted under Section 2(b) shall terminate as of the date such litigation is filed. 

@license_1154_p
# All Recipient's rights under this Agreement shall terminate if it fails to comply with any of the material terms or conditions of this Agreement and does not cure such failure in a reasonable period of time after becoming aware of such noncompliance. If all Recipient's rights under this Agreement terminate, Recipient agrees to cease use and distribution of the Program as soon as reasonably practicable. However, Recipient's obligations under this Agreement and any licenses granted by Recipient relating to the Program shall continue and survive. 

@license_1155_p
# Everyone is permitted to copy and distribute copies of this Agreement, but in order to avoid inconsistency the Agreement is copyrighted and may only be modified in the following manner. The Agreement Steward reserves the right to publish new versions (including revisions) of this Agreement from time to time. No one other than the Agreement Steward has the right to modify this Agreement. The Eclipse Foundation is the initial Agreement Steward. The Eclipse Foundation may assign the responsibility to serve as the Agreement Steward to a suitable separate entity. Each new version of the Agreement will be given a distinguishing version number. The Program (including Contributions) may always be distributed subject to the version of the Agreement under which it was received. In addition, after a new version of the Agreement is published, Contributor may elect to distribute the Program (including its Contributions) under the new version. Except as expressly stated in Sections 2(a) and 2(b) above, Recipient receives no rights or licenses to the intellectual property of any Contributor under this Agreement, whether expressly, by implication, estoppel or otherwise. All rights in the Program not expressly granted under this Agreement are reserved. 

@license_1156_p
# This Agreement is governed by the laws of the State of New York and the intellectual property laws of the United States of America. No party to this Agreement will bring a legal action under this Agreement more than one year after the cause of action arose. Each party waives its rights to a jury trial in any resulting litigation. 

@links_1000_h1
#H2 In Use and Links

@links_1001_p
# Those are just a few links to products using or supporting H2. If you want to add a link, please send it to the support email address or post it in the group. 

@links_1002_h2
#Books

@links_1003_a
# Seam In Action

@links_1004_h2
#Extensions

@links_1005_a
# Grails H2 Database Plugin

@links_1006_a
# h2osgi: OSGi for the H2 Database

@links_1007_a
# H2Sharp: ADO.NET interface for the H2 database engine

@links_1008_a
# H2 Spatial: spatial functions to H2 database

@links_1009_h2
#Blog Articles

@links_1010_a
# Analyzing CSVs with H2 in under 10 minutes (2009-12-07)

@links_1011_a
# Efficient sorting and iteration on large databases (2009-06-15)

@links_1012_a
# Porting Flexive to the H2 Database (2008-12-05)

@links_1013_a
# H2 Database with GlassFish (2008-11-24)

@links_1014_a
# Using H2 Database with Glassfish and Toplink (2008-08-07)

@links_1015_a
# H2 Database - Performance Tracing (2008-04-30)

@links_1016_a
# Testing your JDBC data access layer with DBUnit and H2 (2007-09-18)

@links_1017_a
# Open Source Databases Comparison (2007-09-11)

@links_1018_a
# The Codist: The Open Source Frameworks I Use (2007-07-23)

@links_1019_a
# The Codist: SQL Injections: How Not To Get Stuck (2007-05-08)

@links_1020_a
# One Man Band: (Helma + H2) == "to easy" (2007-03-11)

@links_1021_a
# David Coldrick's Weblog: New Version of H2 Database Released (2007-01-06)

@links_1022_a
# The Codist: Write Your Own Database, Again (2006-11-13)

@links_1023_h2
#Project Pages

@links_1024_a
# Ohloh

@links_1025_a
# Freshmeat Project Page

@links_1026_a
# Free Open Source Software For Us

@links_1027_a
# Wikipedia

@links_1028_a
# Java Source Net

@links_1029_a
# Linux Package Manager

@links_1030_h2
#Database Frontends / Tools

@links_1031_a
# DB Solo

@links_1032_p
# SQL query tool. 

@links_1033_a
# DbVisualizer

@links_1034_p
# Database tool. 

@links_1035_a
# Execute Query

@links_1036_p
# Database utility written in Java. 

@links_1037_a
# [fleXive]

@links_1038_p
# JavaEE 5 open source framework for the development of complex and evolving (web-)applications. 

@links_1039_a
# HenPlus

@links_1040_p
# HenPlus is a SQL shell written in Java. 

@links_1041_a
# RazorSQL

@links_1042_p
# An SQL query tool, database browser, SQL editor, and database administration tool. 

@links_1043_a
# SQL Developer

@links_1044_p
# Universal Database Frontend. 

@links_1045_a
# SQL Workbench/J

@links_1046_p
# Free DBMS-independent SQL tool. 

@links_1047_a
# SQuirreL SQL Client

@links_1048_p
# Graphical tool to view the structure of a database, browse the data, issue SQL commands etc. 

@links_1049_a
# SQuirreL DB Copy Plugin

@links_1050_p
# Tool to copy data from one database to another. 

@links_1051_h2
#Products and Projects

@links_1052_a
# AccuProcess

@links_1053_p
# Visual business process modeling and simulation software for business users. 

@links_1054_a
# Adeptia BPM

@links_1055_p
# A Business Process Management (BPM) suite to quickly and easily automate business processes and workflows. 

@links_1056_a
# Adeptia Integration

@links_1057_p
# Process-centric, services-based application integration suite. 

@links_1058_a
# Aejaks

@links_1059_p
# A server-side scripting environment to build AJAX enabled web applications. 

@links_1060_a
# Axiom Stack

@links_1061_p
# A web framework that let's you write dynamic web applications with Zen-like simplicity. 

@links_1062_a
# Apache Cayenne

@links_1063_p
# Open source persistence framework providing object-relational mapping (ORM) and remoting services. 

@links_1064_a
# Apache Jackrabbit

@links_1065_p
# Open source implementation of the Java Content Repository API (JCR). 

@links_1066_a
# Apache OpenJPA

@links_1067_p
# Open source implementation of the Java Persistence API (JPA). 

@links_1068_a
# AppFuse

@links_1069_p
# Helps building web applications. 

@links_1070_a
# BGBlitz

@links_1071_p
# The Swiss army knife of Backgammon. 

@links_1072_a
# Blojsom

@links_1073_p
# Java-based multi-blog, multi-user software package (Mac OS X Weblog Server). 

@links_1074_a
# Bonita

@links_1075_p
# Open source workflow solution for handing long-running, user-oriented processes providing out of the box workflow and business process management features. 

@links_1076_a
# Bookmarks Portlet

@links_1077_p
# JSR 168 compliant bookmarks management portlet application. 

@links_1078_a
# Claros inTouch

@links_1079_p
# Ajax communication suite with mail, addresses, notes, IM, and rss reader. 

@links_1080_a
# CrashPlan PRO Server

@links_1081_p
# Easy and cross platform backup solution for business and service providers. 

@links_1082_a
# DbUnit

@links_1083_p
# A JUnit extension (also usable with Ant) targeted for database-driven projects. 

@links_1084_a
# Dinamica Framework

@links_1085_p
# Ajax/J2EE framework for RAD development (mainly oriented toward hispanic markets). 

@links_1086_a
# Ebean ORM Persistence Layer

@links_1087_p
# Open source Java Object Relational Mapping tool. 

@links_1088_a
# Eclipse CDO

@links_1089_p
# The CDO (Connected Data Objects) Model Repository is a distributed shared model framework for EMF models, and a fast server-based O/R mapping solution. 

@links_1090_a
# Epictetus

@links_1091_p
# Free cross platform database tool. 

@links_1092_a
# Fabric3

@links_1093_p
# Fabric3 is a project implementing a federated service network based on the Service Component Architecture specification (http://www.osoa.org). 

@links_1094_a
# FIT4Data

@links_1095_p
# A testing framework for data management applications built on the Java implementation of FIT. 

@links_1096_a
# Flux

@links_1097_p
# Java job scheduler, file transfer, workflow, and BPM. 

@links_1098_a
# GBIF Integrated Publishing Toolkit (IPT)

@links_1099_p
# The GBIF IPT is an open source, Java based web application that connects and serves three types of biodiversity data: taxon primary occurrence data, taxon checklists and general resource metadata. 

@links_1100_a
# GNU Gluco Control

@links_1101_p
# Helps you to manage your diabetes. 

@links_1102_a
# Golden T Studios

@links_1103_p
# Fun-to-play games with a simple interface. 

@links_1104_a
# Group Session

@links_1105_p
# Open source web groupware. 

@links_1106_a
# HA-JDBC

@links_1107_p
# High-Availability JDBC: A JDBC proxy that provides light-weight, transparent, fault tolerant clustering capability to any underlying JDBC driver. 

@links_1108_a
# Harbor

@links_1109_p
# Pojo Application Server. 

@links_1110_a
# Hibernate

@links_1111_p
# Relational persistence for idiomatic Java (O-R mapping tool). 

@links_1112_a
# Hibicius

@links_1113_p
# Online Banking Client for the HBCI protocol. 

@links_1114_a
# ImageMapper

@links_1115_p
# ImageMapper frees users from having to use file browsers to view their images. They get fast access to images and easy cataloguing of them via a user friendly interface. 

@links_1116_a
# JAMWiki

@links_1117_p
# Java-based Wiki engine. 

@links_1118_a
# Jala

@links_1119_p
# Open source collection of JavaScript modules. 

@links_1120_a
# Java Simon

@links_1121_p
# Simple Monitoring API. 

@links_1122_a
# JBoss jBPM

@links_1123_p
# A platform for executable process languages ranging from business process management (BPM) over workflow to service orchestration. 

@links_1124_a
# JBoss Jopr

@links_1125_p
# An enterprise management solution for JBoss middleware projects and other application technologies. 

@links_1126_a
# JGeocoder

@links_1127_p
# Free Java geocoder. Geocoding is the process of estimating a latitude and longitude for a given location. 

@links_1128_a
# JGrass

@links_1129_p
# Java Geographic Resources Analysis Support System. Free, multi platform, open source GIS based on the GIS framework of uDig. 

@links_1130_a
# Jena

@links_1131_p
# Java framework for building Semantic Web applications. 

@links_1132_a
# JMatter

@links_1133_p
# Framework for constructing workgroup business applications based on the Naked Objects Architectural Pattern. 

@links_1134_a
# JotBot

@links_1135_p
# Records your day at user defined intervals. 

@links_1136_a
# JPOX

@links_1137_p
# Java persistent objects. 

@links_1138_a
# Liftweb

@links_1139_p
# A Scala-based, secure, developer friendly web framework. 

@links_1140_a
# LiquiBase

@links_1141_p
# A tool to manage database changes and refactorings. 

@links_1142_a
# Luntbuild

@links_1143_p
# Build automation and management tool. 

@links_1144_a
# localdb

@links_1145_p
# A tool that locates the full file path of the folder containing the database files. 

@links_1146_a
# Magnolia

@links_1147_p
# Microarray Data Management and Export System for PFGRC (Pathogen Functional Genomics Resource Center) Microarrays. 

@links_1148_a
# MiniConnectionPoolManager

@links_1149_p
# A lightweight standalone JDBC connection pool manager. 

@links_1150_a
# Mr. Persister

@links_1151_p
# Simple, small and fast object relational mapping. 

@links_1152_a
# Myna Application Server

@links_1153_p
# Java web app that provides dynamic web content and Java libraries access from JavaScript. 

@links_1154_a
# MyTunesRss

@links_1155_p
# MyTunesRSS lets you listen to your music wherever you are. 

@links_1156_a
# NCGC CurveFit

@links_1157_p
# From: NIH Chemical Genomics Center, National Institutes of Health, USA. An open source application in the life sciences research field. This application handles chemical structures and biological responses of thousands of compounds with the potential to handle million+ compounds. It utilizes an embedded H2 database to enable flexible query/retrieval of all data including advanced chemical substructure and similarity searching. The application highlights an automated curve fitting and classification algorithm that outperforms commercial packages in the field. Commercial alternatives are typically small desktop software that handle a few dose response curves at a time. A couple of commercial packages that do handle several thousand curves are very expensive tools (&gt;60k USD) that require manual curation of analysis by the user; require a license to Oracle; lack advanced query/retrieval; and the ability to handle chemical structures. 

@links_1158_a
# Nuxeo

@links_1159_p
# Standards-based, open source platform for building ECM applications. 

@links_1160_a
# nWire

@links_1161_p
# Eclipse plug-in which expedites Java development. It's main purpose is to help developers find code quicker and easily understand how it relates to the rest of the application, thus, understand the application structure. 

@links_1162_a
# Ontology Works

@links_1163_p
# This company provides semantic technologies including deductive information repositories (the Ontology Works Knowledge Servers), semantic information fusion and semantic federation of legacy databases, ontology-based domain modeling, and management of the distributed enterprise. 

@links_1164_a
# Ontoprise OntoBroker

@links_1165_p
# SemanticWeb-Middleware. It supports all W3C Semantic Web recommendations: OWL, RDF, RDFS, SPARQL, and F-Logic. 

@links_1166_a
# Open Anzo

@links_1167_p
# Semantic Application Server. 

@links_1168_a
# OpenGroove

@links_1169_p
# OpenGroove is a groupware program that allows users to synchronize data. 

@links_1170_a
# OpenSocial Development Environment (OSDE)

@links_1171_p
# Development tool for OpenSocial application. 

@links_1172_a
# Orion

@links_1173_p
# J2EE Application Server. 

@links_1174_a
# P5H2

@links_1175_p
# A library for the <a href="http://www.processing.org">Processing</a> programming language and environment. 

@links_1176_a
# Phase-6

@links_1177_p
# A computer based learning software. 

@links_1178_a
# Pickle

@links_1179_p
# Pickle is a Java library containing classes for persistence, concurrency, and logging. 

@links_1180_a
# Piman

@links_1181_p
# Water treatment projects data management. 

@links_1182_a
# PolePosition

@links_1183_p
# Open source database benchmark. 

@links_1184_a
# Poormans

@links_1185_p
# Very basic CMS running as a SWT application and generating static html pages. 

@links_1186_a
# Railo

@links_1187_p
# Railo is an alternative engine for the Cold Fusion Markup Language, that compiles code programmed in CFML into Java bytecode and executes it on a servlet engine. 

@links_1188_a
# Razuna

@links_1189_p
# Open source Digital Asset Management System with integrated Web Content Management. 

@links_1190_a
# RIFE

@links_1191_p
# A full-stack web application framework with tools and APIs to implement most common web features. 

@links_1192_a
# Rutema

@links_1193_p
# Rutema is a test execution and management tool for heterogeneous development environments written in Ruby. 

@links_1194_a
# Sava

@links_1195_p
# Open-source web-based content management system. 

@links_1196_a
# Scriptella

@links_1197_p
# ETL (Extract-Transform-Load) and script execution tool. 

@links_1198_a
# Sesar

@links_1199_p
# Dependency Injection Container with Aspect Oriented Programming. 

@links_1200_a
# SemmleCode

@links_1201_p
# Eclipse plugin to help you improve software quality. 

@links_1202_a
# SeQuaLite

@links_1203_p
# A free, light-weight, java data access framework. 

@links_1204_a
# ShapeLogic

@links_1205_p
# Toolkit for declarative programming, image processing and computer vision. 

@links_1206_a
# Shellbook

@links_1207_p
# Desktop publishing application. 

@links_1208_a
# Signsoft intelliBO

@links_1209_p
# Persistence middleware supporting the JDO specification. 

@links_1210_a
# SimpleORM

@links_1211_p
# Simple Java Object Relational Mapping. 

@links_1212_a
# SymmetricDS

@links_1213_p
# A web-enabled, database independent, data synchronization/replication software. 

@links_1214_a
# SmartFoxServer

@links_1215_p
# Platform for developing multiuser applications and games with Macromedia Flash. 

@links_1216_a
# Social Bookmarks Friend Finder

@links_1217_p
# A GUI application that allows you to find users with similar bookmarks to the user specified (for delicious.com). 

@links_1218_a
# Springfuse

@links_1219_p
# Code generation For Spring, Spring MVC &amp; Hibernate. 

@links_1220_a
# SQLOrm

@links_1221_p
# Java Object Relation Mapping. 

@links_1222_a
# StorYBook

@links_1223_p
# A summary-based tool for novelist and script writers. It helps to keep the overview over the various traces a story has. 

@links_1224_a
# StreamCruncher

@links_1225_p
# Event (stream) processing kernel. 

@links_1226_a
# Tune Backup

@links_1227_p
# Easy-to-use backup solution for your iTunes library. 

@links_1228_a
# weblica

@links_1229_p
# Desktop CMS. 

@links_1230_a
# Web of Web

@links_1231_p
# Collaborative and realtime interactive media platform for the web. 

@links_1232_a
# Werkzeugkasten

@links_1233_p
# Minimum Java Toolset. 

@links_1234_a
# VPDA

@links_1235_p
# View providers driven applications is a Java based application framework for building applications composed from server components - view providers. 

@links_1236_a
# Volunteer database

@links_1237_p
# A database front end to register volunteers, partnership and donation for a Non Profit organization. 

@mainWeb_1000_h1
H2 データベース エンジン

@mainWeb_1001_p
# Welcome to H2, the Java SQL database. The main features of H2 are: 

@mainWeb_1002_li
#Very fast, open source, JDBC API 

@mainWeb_1003_li
#Embedded and server modes; in-memory databases 

@mainWeb_1004_li
#Browser based Console application 

@mainWeb_1005_li
#Small footprint: around 1 MB jar file size 

@mainWeb_1006_h3
ダウンロード

@mainWeb_1007_td
# Version 1.2.135 (2010-05-08): 

@mainWeb_1008_a
#Windows Installer (4 MB)

@mainWeb_1009_a
#All Platforms (zip, 5 MB)

@mainWeb_1010_a
#All Downloads

@mainWeb_1011_td
&nbsp;&nbsp;&nbsp;

@mainWeb_1012_h3
サポート

@mainWeb_1013_a
Google グループ (English)

@mainWeb_1014_a
Google グループ (Japanese)

@mainWeb_1015_p
# For non-technical issues, use: 

@mainWeb_1016_h3
特徴

@mainWeb_1017_th
H2

@mainWeb_1018_a
Derby

@mainWeb_1019_a
HSQLDB

@mainWeb_1020_a
MySQL

@mainWeb_1021_a
PostgreSQL

@mainWeb_1022_td
Pure Java

@mainWeb_1023_td
対応

@mainWeb_1024_td
対応

@mainWeb_1025_td
対応

@mainWeb_1026_td
非対応

@mainWeb_1027_td
非対応

@mainWeb_1028_td
#Memory Mode

@mainWeb_1029_td
対応

@mainWeb_1030_td
対応

@mainWeb_1031_td
対応

@mainWeb_1032_td
非対応

@mainWeb_1033_td
非対応

@mainWeb_1034_td
トランザクション分離

@mainWeb_1035_td
対応

@mainWeb_1036_td
対応

@mainWeb_1037_td
非対応

@mainWeb_1038_td
対応

@mainWeb_1039_td
対応

@mainWeb_1040_td
コストベースオプティマイザ

@mainWeb_1041_td
対応

@mainWeb_1042_td
対応

@mainWeb_1043_td
非対応

@mainWeb_1044_td
対応

@mainWeb_1045_td
対応

@mainWeb_1046_td
暗号化データベース

@mainWeb_1047_td
対応

@mainWeb_1048_td
対応

@mainWeb_1049_td
非対応

@mainWeb_1050_td
非対応

@mainWeb_1051_td
非対応

@mainWeb_1052_td
ODBCドライバ

@mainWeb_1053_td
対応

@mainWeb_1054_td
非対応

@mainWeb_1055_td
非対応

@mainWeb_1056_td
対応

@mainWeb_1057_td
対応

@mainWeb_1058_td
フルテキストサーチ

@mainWeb_1059_td
対応

@mainWeb_1060_td
非対応

@mainWeb_1061_td
非対応

@mainWeb_1062_td
対応

@mainWeb_1063_td
対応

@mainWeb_1064_td
#Multi Version Concurrency

@mainWeb_1065_td
対応

@mainWeb_1066_td
非対応

@mainWeb_1067_td
非対応

@mainWeb_1068_td
対応

@mainWeb_1069_td
対応

@mainWeb_1070_td
フットプリント (jar/dll size)

@mainWeb_1071_td
#~1 MB

@mainWeb_1072_td
#~2 MB

@mainWeb_1073_td
#~600 KB

@mainWeb_1074_td
#~4 MB

@mainWeb_1075_td
#~6 MB

@mainWeb_1076_p
# See also the <a href="features.html#comparison">detailed comparison</a>. 

@mainWeb_1077_h3
ニュース

@mainWeb_1078_b
ニュースフィード:

@mainWeb_1079_a
#Full text (Atom)

@mainWeb_1080_p
# or <a href="http://www.h2database.com/html/newsfeed-rss.xml">Header only (RSS)</a>. 

@mainWeb_1081_b
Email ニュースレター:

@mainWeb_1082_p
# Subscribe to <a href="http://groups.google.com/group/h2database-news/subscribe"> H2 Database News (Google account required)</a> to get informed about new releases. Your email address is only used in this context. 

@mainWeb_1083_td
&nbsp;

@mainWeb_1084_h3
寄稿する

@mainWeb_1085_p
# You can contribute to the development of H2 by sending feedback and bug reports, or translate the H2 Console application (for details, start the H2 Console and select Options / Translate). To donate money, click on the PayPal button below. You will be listed as a supporter: 

@main_1000_h1
H2 データベース エンジン

@main_1001_p
# Welcome to H2, the free Java SQL database engine. 

@main_1002_a
クイックスタート

@main_1003_p
# Get a fast overview. 

@main_1004_a
チュートリアル

@main_1005_p
# Go through the samples. 

@main_1006_a
特徴

@main_1007_p
# See what this database can do and how to use these features. 

@performance_1000_h1
パフォーマンス

@performance_1001_a
# Performance Comparison

@performance_1002_a
# PolePosition Benchmark

@performance_1003_a
# Application Profiling

@performance_1004_a
# Database Profiling

@performance_1005_a
# Database Performance Tuning

@performance_1006_a
# Using the Built-In Profiler

@performance_1007_a
# Fast Database Import

@performance_1008_h2
#Performance Comparison

@performance_1009_p
# In many cases H2 is faster than other (open source and not open source) database engines. Please note this is mostly a single connection benchmark run on one computer. 

@performance_1010_h3
#Embedded

@performance_1011_th
#Test Case

@performance_1012_th
#Unit

@performance_1013_th
H2

@performance_1014_th
HSQLDB

@performance_1015_th
Derby

@performance_1016_td
#Simple: Init

@performance_1017_td
#ms

@performance_1018_td
#547

@performance_1019_td
#532

@performance_1020_td
#2594

@performance_1021_td
#Simple: Query (random)

@performance_1022_td
#ms

@performance_1023_td
#250

@performance_1024_td
#391

@performance_1025_td
#1515

@performance_1026_td
#Simple: Query (sequential)

@performance_1027_td
#ms

@performance_1028_td
#188

@performance_1029_td
#313

@performance_1030_td
#1406

@performance_1031_td
#Simple: Update (random)

@performance_1032_td
#ms

@performance_1033_td
#812

@performance_1034_td
#1750

@performance_1035_td
#17704

@performance_1036_td
#Simple: Delete (sequential)

@performance_1037_td
#ms

@performance_1038_td
#203

@performance_1039_td
#250

@performance_1040_td
#8843

@performance_1041_td
#Simple: Memory Usage

@performance_1042_td
#MB

@performance_1043_td
#7

@performance_1044_td
#11

@performance_1045_td
#11

@performance_1046_td
#BenchA: Init

@performance_1047_td
#ms

@performance_1048_td
#578

@performance_1049_td
#719

@performance_1050_td
#3328

@performance_1051_td
#BenchA: Transactions

@performance_1052_td
#ms

@performance_1053_td
#3047

@performance_1054_td
#2406

@performance_1055_td
#12907

@performance_1056_td
#BenchA: Memory Usage

@performance_1057_td
#MB

@performance_1058_td
#10

@performance_1059_td
#15

@performance_1060_td
#10

@performance_1061_td
#BenchB: Init

@performance_1062_td
#ms

@performance_1063_td
#2141

@performance_1064_td
#2406

@performance_1065_td
#11562

@performance_1066_td
#BenchB: Transactions

@performance_1067_td
#ms

@performance_1068_td
#1125

@performance_1069_td
#1375

@performance_1070_td
#3625

@performance_1071_td
#BenchB: Memory Usage

@performance_1072_td
#MB

@performance_1073_td
#9

@performance_1074_td
#11

@performance_1075_td
#8

@performance_1076_td
#BenchC: Init

@performance_1077_td
#ms

@performance_1078_td
#688

@performance_1079_td
#594

@performance_1080_td
#4500

@performance_1081_td
#BenchC: Transactions

@performance_1082_td
#ms

@performance_1083_td
#1906

@performance_1084_td
#64062

@performance_1085_td
#6047

@performance_1086_td
#BenchC: Memory Usage

@performance_1087_td
#MB

@performance_1088_td
#11

@performance_1089_td
#17

@performance_1090_td
#11

@performance_1091_td
#Executed statements

@performance_1092_td
##

@performance_1093_td
#322929

@performance_1094_td
#322929

@performance_1095_td
#322929

@performance_1096_td
#Total time

@performance_1097_td
#ms

@performance_1098_td
#11485

@performance_1099_td
#74798

@performance_1100_td
#74031

@performance_1101_td
#Statements per second

@performance_1102_td
##

@performance_1103_td
#28117

@performance_1104_td
#4317

@performance_1105_td
#4362

@performance_1106_h3
#Client-Server

@performance_1107_th
#Test Case

@performance_1108_th
#Unit

@performance_1109_th
H2

@performance_1110_th
HSQLDB

@performance_1111_th
Derby

@performance_1112_th
PostgreSQL

@performance_1113_th
MySQL

@performance_1114_td
#Simple: Init

@performance_1115_td
#ms

@performance_1116_td
#2782

@performance_1117_td
#2656

@performance_1118_td
#5625

@performance_1119_td
#4563

@performance_1120_td
#3484

@performance_1121_td
#Simple: Query (random)

@performance_1122_td
#ms

@performance_1123_td
#3093

@performance_1124_td
#2703

@performance_1125_td
#6688

@performance_1126_td
#4812

@performance_1127_td
#3860

@performance_1128_td
#Simple: Query (sequential)

@performance_1129_td
#ms

@performance_1130_td
#2969

@performance_1131_td
#2594

@performance_1132_td
#6437

@performance_1133_td
#4719

@performance_1134_td
#3625

@performance_1135_td
#Simple: Update (random)

@performance_1136_td
#ms

@performance_1137_td
#2969

@performance_1138_td
#3531

@performance_1139_td
#18250

@performance_1140_td
#5953

@performance_1141_td
#5125

@performance_1142_td
#Simple: Delete (sequential)

@performance_1143_td
#ms

@performance_1144_td
#1047

@performance_1145_td
#1250

@performance_1146_td
#6875

@performance_1147_td
#2485

@performance_1148_td
#2390

@performance_1149_td
#Simple: Memory Usage

@performance_1150_td
#MB

@performance_1151_td
#7

@performance_1152_td
#11

@performance_1153_td
#14

@performance_1154_td
#0

@performance_1155_td
#0

@performance_1156_td
#BenchA: Init

@performance_1157_td
#ms

@performance_1158_td
#2250

@performance_1159_td
#2453

@performance_1160_td
#6031

@performance_1161_td
#4328

@performance_1162_td
#3625

@performance_1163_td
#BenchA: Transactions

@performance_1164_td
#ms

@performance_1165_td
#10250

@performance_1166_td
#9016

@performance_1167_td
#21484

@performance_1168_td
#15609

@performance_1169_td
#11172

@performance_1170_td
#BenchA: Memory Usage

@performance_1171_td
#MB

@performance_1172_td
#10

@performance_1173_td
#15

@performance_1174_td
#10

@performance_1175_td
#0

@performance_1176_td
#1

@performance_1177_td
#BenchB: Init

@performance_1178_td
#ms

@performance_1179_td
#9500

@performance_1180_td
#10672

@performance_1181_td
#22609

@performance_1182_td
#19609

@performance_1183_td
#13406

@performance_1184_td
#BenchB: Transactions

@performance_1185_td
#ms

@performance_1186_td
#2734

@performance_1187_td
#2656

@performance_1188_td
#3875

@performance_1189_td
#4688

@performance_1190_td
#2531

@performance_1191_td
#BenchB: Memory Usage

@performance_1192_td
#MB

@performance_1193_td
#10

@performance_1194_td
#11

@performance_1195_td
#11

@performance_1196_td
#1

@performance_1197_td
#1

@performance_1198_td
#BenchC: Init

@performance_1199_td
#ms

@performance_1200_td
#1860

@performance_1201_td
#1484

@performance_1202_td
#6890

@performance_1203_td
#2219

@performance_1204_td
#3438

@performance_1205_td
#BenchC: Transactions

@performance_1206_td
#ms

@performance_1207_td
#9046

@performance_1208_td
#63266

@performance_1209_td
#18641

@performance_1210_td
#11703

@performance_1211_td
#7421

@performance_1212_td
#BenchC: Memory Usage

@performance_1213_td
#MB

@performance_1214_td
#12

@performance_1215_td
#17

@performance_1216_td
#13

@performance_1217_td
#0

@performance_1218_td
#1

@performance_1219_td
#Executed statements

@performance_1220_td
##

@performance_1221_td
#322929

@performance_1222_td
#322929

@performance_1223_td
#322929

@performance_1224_td
#322929

@performance_1225_td
#322929

@performance_1226_td
#Total time

@performance_1227_td
#ms

@performance_1228_td
#48500

@performance_1229_td
#102281

@performance_1230_td
#123405

@performance_1231_td
#80688

@performance_1232_td
#60077

@performance_1233_td
#Statements per second

@performance_1234_td
##

@performance_1235_td
#6658

@performance_1236_td
#3157

@performance_1237_td
#2616

@performance_1238_td
#4002

@performance_1239_td
#5375

@performance_1240_h3
#Benchmark Results and Comments

@performance_1241_h4
H2

@performance_1242_p
# Version 1.1.114 (2009-06-01) was used for the test. For simpler operations, the performance of H2 is about the same as for HSQLDB. For more complex queries, the query optimizer is very important. However H2 is not very fast in every case, certain kind of queries may still be slow. One situation where is H2 is slow is large result sets, because they are buffered to disk if more than a certain number of records are returned. The advantage of buffering is, there is no limit on the result set size. The open/close time is almost fixed, because of the file locking protocol: the engine waits some time after opening a database to ensure the database files are not opened by another process. 

@performance_1243_h4
HSQLDB

@performance_1244_p
# Version 1.8.0.10 was used for the test. Cached tables are used in this test (hsqldb.default_table_type=cached), and the write delay is 1 second (<code>SET WRITE_DELAY 1</code>). HSQLDB is fast when using simple operations. HSQLDB is very slow in the last test (BenchC: Transactions), probably because is has a bad query optimizer. One query where HSQLDB is slow is a two-table join: 

@performance_1245_p
# The PolePosition benchmark also shows that the query optimizer does not do a very good job for some queries. Another disadvantage of HSQLDB is the slow startup / shutdown time (currently not listed) when using bigger databases. The reason is, a backup of the whole data is made whenever the database is opened or closed. 

@performance_1246_h4
Derby

@performance_1247_p
# Version 10.4.2.0 was used for the test. Derby is clearly the slowest embedded database in this test. This seems to be a structural problem, because all operations are really slow. It will be hard for the developers of Derby to improve the performance to a reasonable level. A few problems have been identified: leaving autocommit on is a problem for Derby. If it is switched off during the whole test, the results are about 20% better for Derby. Derby does not call FileDescriptor.sync() or FileChannel.force(..) on each commit. Derby supports a testing mode (system property <code>derby.system.durability=test</code>) where durability is disabled. According to the documentation, this setting should be used for testing only, as the database may not recover after a crash. Enabling this setting improves performance by a factor of 2.6 (embedded mode) or 1.4 (server mode). Even if enabled, Derby is still less than half as fast as H2 in default mode. 

@performance_1248_h4
PostgreSQL

@performance_1249_p
# Version 8.3.7 was used for the test. The following options where changed in <code>postgresql.conf: fsync = off, commit_delay = 1000</code>. PostgreSQL is run in server mode. It looks like the base performance is slower than MySQL, the reason could be the network layer. The memory usage number is incorrect, because only the memory usage of the JDBC driver is measured. 

@performance_1250_h4
MySQL

@performance_1251_p
# Version 5.1.34-community was used for the test. MySQL was run with the InnoDB backend. The setting <code>innodb_flush_log_at_trx_commit</code> (found in the <code>my.ini</code> file) was set to 0. Otherwise (and by default), MySQL is really slow (around 140 statements per second in this test) because it tries to flush the data to disk for each commit. For small transactions (when autocommit is on) this is really slow. But many use cases use small or relatively small transactions. Too bad this setting is not listed in the configuration wizard, and it always overwritten when using the wizard. You need to change this setting manually in the file <code>my.ini</code>, and then restart the service. The memory usage number is incorrect, because only the memory usage of the JDBC driver is measured. 

@performance_1252_h4
#Firebird

@performance_1253_p
# Firebird 1.5 (default installation) was tested, but the results are not published currently. It is possible to run the performance test with the Firebird database, and any information on how to configure Firebird for higher performance are welcome. 

@performance_1254_h4
#Why Oracle / MS SQL Server / DB2 are Not Listed

@performance_1255_p
# The license of these databases does not allow to publish benchmark results. This doesn't mean that they are fast. They are in fact quite slow, and need a lot of memory. But you will need to test this yourself. SQLite was not tested because the JDBC driver doesn't support transactions. 

@performance_1256_h3
#About this Benchmark

@performance_1257_h4
#How to Run

@performance_1258_p
# This test was executed as follows: 

@performance_1259_h4
#Separate Process per Database

@performance_1260_p
# For each database, a new process is started, to ensure the previous test does not impact the current test. 

@performance_1261_h4
#Number of Connections

@performance_1262_p
# This is mostly a single-connection benchmark. BenchB uses multiple connections; the other tests use one connection. 

@performance_1263_h4
#Real-World Tests

@performance_1264_p
# Good benchmarks emulate real-world use cases. This benchmark includes 4 test cases: BenchSimple uses one table and many small updates / deletes. BenchA is similar to the TPC-A test, but single connection / single threaded (see also: www.tpc.org). BenchB is similar to the TPC-B test, using multiple connections (one thread per connection). BenchC is similar to the TPC-C test, but single connection / single threaded. 

@performance_1265_h4
#Comparing Embedded with Server Databases

@performance_1266_p
# This is mainly a benchmark for embedded databases (where the application runs in the same virtual machine as the database engine). However MySQL and PostgreSQL are not Java databases and cannot be embedded into a Java application. For the Java databases, both embedded and server modes are tested. 

@performance_1267_h4
#Test Platform

@performance_1268_p
# This test is run on Windows XP with the virus scanner switched off. The VM used is Sun JDK 1.5. 

@performance_1269_h4
#Multiple Runs

@performance_1270_p
# When a Java benchmark is run first, the code is not fully compiled and therefore runs slower than when running multiple times. A benchmark should always run the same test multiple times and ignore the first run(s). This benchmark runs three times, but only the last run is measured. 

@performance_1271_h4
#Memory Usage

@performance_1272_p
# It is not enough to measure the time taken, the memory usage is important as well. Performance can be improved by using a bigger cache, but the amount of memory is limited. HSQLDB tables are kept fully in memory by default; this benchmark uses 'disk based' tables for all databases. Unfortunately, it is not so easy to calculate the memory usage of PostgreSQL and MySQL, because they run in a different process than the test. This benchmark currently does not print memory usage of those databases. 

@performance_1273_h4
#Delayed Operations

@performance_1274_p
# Some databases delay some operations (for example flushing the buffers) until after the benchmark is run. This benchmark waits between each database tested, and each database runs in a different process (sequentially). 

@performance_1275_h4
#Transaction Commit / Durability

@performance_1276_p
# Durability means transaction committed to the database will not be lost. Some databases (for example MySQL) try to enforce this by default by calling <code>fsync()</code> to flush the buffers, but most hard drives don't actually flush all data. Calling the method slows down transaction commit a lot, but doesn't always make data durable. When comparing the results, it is important to think about the effect. Many database suggest to 'batch' operations when possible. This benchmark switches off autocommit when loading the data, and calls commit after each 1000 inserts. However many applications need 'short' transactions at runtime (a commit after each update). This benchmark commits after each update / delete in the simple benchmark, and after each business transaction in the other benchmarks. For databases that support delayed commits, a delay of one second is used. 

@performance_1277_h4
#Using Prepared Statements

@performance_1278_p
# Wherever possible, the test cases use prepared statements. 

@performance_1279_h4
#Currently Not Tested: Startup Time

@performance_1280_p
# The startup time of a database engine is important as well for embedded use. This time is not measured currently. Also, not tested is the time used to create a database and open an existing database. Here, one (wrapper) connection is opened at the start, and for each step a new connection is opened and then closed. 

@performance_1281_h2
#PolePosition Benchmark

@performance_1282_p
# The PolePosition is an open source benchmark. The algorithms are all quite simple. It was developed / sponsored by db4o. 

@performance_1283_th
#Test Case

@performance_1284_th
#Unit

@performance_1285_th
H2

@performance_1286_th
HSQLDB

@performance_1287_th
MySQL

@performance_1288_td
#Melbourne write

@performance_1289_td
#ms

@performance_1290_td
#369

@performance_1291_td
#249

@performance_1292_td
#2022

@performance_1293_td
#Melbourne read

@performance_1294_td
#ms

@performance_1295_td
#47

@performance_1296_td
#49

@performance_1297_td
#93

@performance_1298_td
#Melbourne read_hot

@performance_1299_td
#ms

@performance_1300_td
#24

@performance_1301_td
#43

@performance_1302_td
#95

@performance_1303_td
#Melbourne delete

@performance_1304_td
#ms

@performance_1305_td
#147

@performance_1306_td
#133

@performance_1307_td
#176

@performance_1308_td
#Sepang write

@performance_1309_td
#ms

@performance_1310_td
#965

@performance_1311_td
#1201

@performance_1312_td
#3213

@performance_1313_td
#Sepang read

@performance_1314_td
#ms

@performance_1315_td
#765

@performance_1316_td
#948

@performance_1317_td
#3455

@performance_1318_td
#Sepang read_hot

@performance_1319_td
#ms

@performance_1320_td
#789

@performance_1321_td
#859

@performance_1322_td
#3563

@performance_1323_td
#Sepang delete

@performance_1324_td
#ms

@performance_1325_td
#1384

@performance_1326_td
#1596

@performance_1327_td
#6214

@performance_1328_td
#Bahrain write

@performance_1329_td
#ms

@performance_1330_td
#1186

@performance_1331_td
#1387

@performance_1332_td
#6904

@performance_1333_td
#Bahrain query_indexed_string

@performance_1334_td
#ms

@performance_1335_td
#336

@performance_1336_td
#170

@performance_1337_td
#693

@performance_1338_td
#Bahrain query_string

@performance_1339_td
#ms

@performance_1340_td
#18064

@performance_1341_td
#39703

@performance_1342_td
#41243

@performance_1343_td
#Bahrain query_indexed_int

@performance_1344_td
#ms

@performance_1345_td
#104

@performance_1346_td
#134

@performance_1347_td
#678

@performance_1348_td
#Bahrain update

@performance_1349_td
#ms

@performance_1350_td
#191

@performance_1351_td
#87

@performance_1352_td
#159

@performance_1353_td
#Bahrain delete

@performance_1354_td
#ms

@performance_1355_td
#1215

@performance_1356_td
#729

@performance_1357_td
#6812

@performance_1358_td
#Imola retrieve

@performance_1359_td
#ms

@performance_1360_td
#198

@performance_1361_td
#194

@performance_1362_td
#4036

@performance_1363_td
#Barcelona write

@performance_1364_td
#ms

@performance_1365_td
#413

@performance_1366_td
#832

@performance_1367_td
#3191

@performance_1368_td
#Barcelona read

@performance_1369_td
#ms

@performance_1370_td
#119

@performance_1371_td
#160

@performance_1372_td
#1177

@performance_1373_td
#Barcelona query

@performance_1374_td
#ms

@performance_1375_td
#20

@performance_1376_td
#5169

@performance_1377_td
#101

@performance_1378_td
#Barcelona delete

@performance_1379_td
#ms

@performance_1380_td
#388

@performance_1381_td
#319

@performance_1382_td
#3287

@performance_1383_td
#Total

@performance_1384_td
#ms

@performance_1385_td
#26724

@performance_1386_td
#53962

@performance_1387_td
#87112

@performance_1388_p
# There are a few problems with the PolePosition test: 

@performance_1389_li
# HSQLDB uses in-memory tables by default while H2 uses persistent tables. The HSQLDB version included in PolePosition does not support changing this, so you need to replace <code>poleposition-0.20/lib/hsqldb.jar</code> with a newer version (for example <code>hsqldb-1.8.0.7.jar</code>), and then use the setting <code>hsqldb.connecturl=jdbc:hsqldb:file:data/hsqldb/dbbench2;hsqldb.default_table_type=cached;sql.enforce_size=true</code> in the file <code>Jdbc.properties</code>. 

@performance_1390_li
#HSQLDB keeps the database open between tests, while H2 closes the database (losing all the cache). To change that, use the database URL <code>jdbc:h2:file:data/h2/dbbench;DB_CLOSE_DELAY=-1</code> 

@performance_1391_li
#The amount of cache memory is quite important, specially for the PolePosition test. Unfortunately, the PolePosition test does not take this into account. 

@performance_1392_h2
#Application Profiling

@performance_1393_h3
#Analyze First

@performance_1394_p
# Before trying to optimize performance, it is important to understand where the problem is (what part of the application is slow). Blind optimization or optimization based on guesses should be avoided, because usually it is not an efficient strategy. There are various ways to analyze an application. Sometimes two implementations can be compared using <code>System.currentTimeMillis()</code>. But this does not work for complex applications with many modules, and for memory problems. 

@performance_1395_p
# A simple way to profile an application is to use the built-in profiling tool of java. Example: 

@performance_1396_p
# Unfortunately, it is only possible to profile the application from start to end. Another solution is to create a number of full thread dumps. To do that, first run <code>jps -l</code> to get the process id, and then run <code>jstack &lt;pid&gt;</code> or <code>kill -QUIT &lt;pid&gt;</code> (Linux) or press Ctrl+C (Windows). 

@performance_1397_p
# A simple profiling tool is included in H2. To use it, the application needs to be changed slightly. Example: 

@performance_1398_p
# The profiler is built into the H2 Console tool, to analyze databases that open slowly. To use it, run the H2 Console, and then click on 'Test Connection'. Afterwards, click on "Test successful" and you get the most common stack traces, which helps to find out why it took so long to connect. You will only get the stack traces if opening the database took more than a few seconds. 

@performance_1399_h2
#Database Profiling

@performance_1400_p
# The <code>ConvertTraceFile</code> tool generates SQL statement statistics at the end of the SQL script file. The format used is similar to the profiling data generated when using <code>java -Xrunhprof</code>. As an example, execute the the following script using the H2 Console: 

@performance_1401_p
# Now convert the <code>.trace.db</code> file using the <code>ConvertTraceFile</code> tool: 

@performance_1402_p
# The generated file <code>test.sql</code> will contain the SQL statements as well as the following profiling data (results vary): 

@performance_1403_h2
#Database Performance Tuning

@performance_1404_h3
#Keep Connections Open or Use a Connection Pool

@performance_1405_p
# If your application opens and closes connections a lot (for example, for each request), you should consider using a <a href="tutorial.html#connection_pool">connection pool</a>. Opening a connection using <code>DriverManager.getConnection</code> is specially slow if the database is closed. By default the database is closed if the last connection is closed. 

@performance_1406_p
# If you open and close connections a lot but don't want to use a connection pool, consider keeping a 'sentinel' connection open for as long as the application runs, or use delayed database closing. See also <a href="features.html#closing_a_database">Closing a database</a>. 

@performance_1407_h3
#Use a Modern JVM

@performance_1408_p
# Newer JVMs are faster. Upgrading to the latest version of your JVM can provide a "free" boost to performance. Switching from the default Client JVM to the Server JVM using the <code>-server</code> command-line option improves performance at the cost of a slight increase in start-up time. 

@performance_1409_h3
#Virus Scanners

@performance_1410_p
# Some virus scanners scan files every time they are accessed. It is very important for performance that database files are not scanned for viruses. The database engine never interprets the data stored in the files as programs, that means even if somebody would store a virus in a database file, this would be harmless (when the virus does not run, it cannot spread). Some virus scanners allow to exclude files by suffix. Ensure files ending with <code>.db</code> are not scanned. 

@performance_1411_h3
トレースオプションを使用する

@performance_1412_p
# If the performance hot spots are in the database engine, in many cases the performance can be optimized by creating additional indexes, or changing the schema. Sometimes the application does not directly generate the SQL statements, for example if an O/R mapping tool is used. To view the SQL statements and JDBC API calls, you can use the trace options. For more information, see <a href="features.html#trace_options">Using the Trace Options</a>. 

@performance_1413_h3
#Index Usage

@performance_1414_p
# This database uses indexes to improve the performance of <code>SELECT, UPDATE, DELETE</code>. If a column is used in the <code>WHERE</code> clause of a query, and if an index exists on this column, then the index can be used. Multi-column indexes are used if all or the first columns of the index are used. Both equality lookup and range scans are supported. Indexes are used to order result sets, but only if the condition uses the same index or no index at all. The results are sorted in memory if required. Indexes are created automatically for primary key and unique constraints. Indexes are also created for foreign key constraints, if required. For other columns, indexes need to be created manually using the <code>CREATE INDEX</code> statement. 

@performance_1415_h3
#Optimizer

@performance_1416_p
# This database uses a cost based optimizer. For simple and queries and queries with medium complexity (less than 7 tables in the join), the expected cost (running time) of all possible plans is calculated, and the plan with the lowest cost is used. For more complex queries, the algorithm first tries all possible combinations for the first few tables, and the remaining tables added using a greedy algorithm (this works well for most joins). Afterwards a genetic algorithm is used to test at most 2000 distinct plans. Only left-deep plans are evaluated. 

@performance_1417_h3
#Expression Optimization

@performance_1418_p
# After the statement is parsed, all expressions are simplified automatically if possible. Operations are evaluated only once if all parameters are constant. Functions are also optimized, but only if the function is constant (always returns the same result for the same parameter values). If the <code>WHERE</code> clause is always false, then the table is not accessed at all. 

@performance_1419_h3
#COUNT(*) Optimization

@performance_1420_p
# If the query only counts all rows of a table, then the data is not accessed. However, this is only possible if no <code>WHERE</code> clause is used, that means it only works for queries of the form <code>SELECT COUNT(*) FROM table</code>. 

@performance_1421_h3
#Updating Optimizer Statistics / Column Selectivity

@performance_1422_p
# When executing a query, at most one index per joined table can be used. If the same table is joined multiple times, for each join only one index is used. Example: for the query <code>SELECT * FROM TEST T1, TEST T2 WHERE T1.NAME='A' AND T2.ID=T1.ID</code>, two index can be used, in this case the index on NAME for T1 and the index on ID for T2. 

@performance_1423_p
# If a table has multiple indexes, sometimes more than one index could be used. Example: if there is a table <code>TEST(ID, NAME, FIRSTNAME)</code> and an index on each column, then two indexes could be used for the query <code>SELECT * FROM TEST WHERE NAME='A' AND FIRSTNAME='B'</code>, the index on NAME or the index on FIRSTNAME. It is not possible to use both indexes at the same time. Which index is used depends on the selectivity of the column. The selectivity describes the 'uniqueness' of values in a column. A selectivity of 100 means each value appears only once, and a selectivity of 1 means the same value appears in many or most rows. For the query above, the index on NAME should be used if the table contains more distinct names than first names. 

@performance_1424_p
# The SQL statement <code>ANALYZE</code> can be used to automatically estimate the selectivity of the columns in the tables. This command should be run from time to time to improve the query plans generated by the optimizer. 

@performance_1425_h3
#In-Memory (Hash) Indexes

@performance_1426_p
# Using in-memory indexes, specially in-memory hash indexes, can speed up queries and data manipulation. 

@performance_1427_p
#In-memory indexes are automatically used for in-memory databases, but can also be created for persistent databases using <code>CREATE MEMORY TABLE</code>. In many cases, the rows itself will also be kept in-memory. Please note this may cause memory problems for large tables. 

@performance_1428_p
# In-memory hash indexes are backed by a hash table and are usually faster than regular indexes. However, hash indexes only supports direct lookup (<code>WHERE ID = ?</code>) but not range scan (<code>WHERE ID &lt; ?</code>). To use hash indexes, use HASH as in: <code>CREATE UNIQUE HASH INDEX</code> and <code>CREATE TABLE ...(ID INT PRIMARY KEY HASH,...)</code>. 

@performance_1429_h3
#Use Prepared Statements

@performance_1430_p
# If possible, use prepared statements with parameters. 

@performance_1431_h3
#Prepared Statements and IN(...)

@performance_1432_p
# Avoid generating SQL statements with a variable size IN(...) list. Instead, use a prepared statement with arrays as in the following example: 

@performance_1433_h3
#Optimization Examples

@performance_1434_p
# See <code>src/test/org/h2/samples/optimizations.sql</code> for a few examples of queries that benefit from special optimizations built into the database. 

@performance_1435_h3
#Cache Size and Type

@performance_1436_p
# By default the cache size of H2 is quite small. Consider using a larger cache size, or enable the second level soft reference cache. See also <a href="features.html#cache_settings">Cache Settings</a>. 

@performance_1437_h3
データ型

@performance_1438_p
# Each data type has different storage and performance characteristics: 

@performance_1439_li
#The <code>DECIMAL/NUMERIC</code> type is slower and requires more storage than the <code>REAL</code> and <code>DOUBLE</code> types. 

@performance_1440_li
#Text types are slower to read, write, and compare than numeric types and generally require more storage. 

@performance_1441_li
#See <a href="advanced.html#large_objects">Large Objects</a> for information on <code>BINARY</code> vs. <code>BLOB</code> and <code>VARCHAR</code> vs. <code>CLOB</code> performance. 

@performance_1442_li
#Parsing and formatting takes longer for the <code>TIME</code>, <code>DATE</code>, and <code>TIMESTAMP</code> types than the numeric types. 

@performance_1443_code
#SMALLINT/TINYINT/BOOLEAN

@performance_1444_li
# are not significantly smaller or faster to work with than <code>INTEGER</code> in most modes. 

@performance_1445_h3
#Sorted Insert Optimization

@performance_1446_p
# To reduce disk space usage and speed up table creation, an optimization for sorted inserts is available. When used, b-tree pages are split at the insertion point. To use this optimization, add <code>SORTED</code> before the <code>SELECT</code> statement: 

@performance_1447_h2
#Using the Built-In Profiler

@performance_1448_p
# A very simple Java profiler is built-in. To use it, use the following template: 

@performance_1449_h2
#Fast Database Import

@performance_1450_p
# To speed up large imports, consider using the following options temporarily: 

@performance_1451_code
#SET CACHE_SIZE

@performance_1452_li
# (a large cache is faster) 

@performance_1453_code
#SET LOCK_MODE 0

@performance_1454_li
# (disable locking) 

@performance_1455_code
#SET UNDO_LOG 0

@performance_1456_li
# (disable the session undo log) 

@performance_1457_p
# These options can be set in the database URL: <code>jdbc:h2:~/test;CACHE_SIZE=65536;LOCK_MODE=0;UNDO_LOG=0</code>. Most of those options are not recommended for regular use, that means you need to reset them after use. 

@quickstart_1000_h1
クイックスタート

@quickstart_1001_a
# Embedding H2 in an Application

@quickstart_1002_a
# The H2 Console Application

@quickstart_1003_h2
アプリケーションのエンベッドH2

@quickstart_1004_p
# This database can be used in embedded mode, or in server mode. To use it in embedded mode, you need to: 

@quickstart_1005_li
#Add the <code>h2*.jar</code> to the classpath (H2 does not have any dependencies) 

@quickstart_1006_li
#Use the JDBC driver class: <code>org.h2.Driver</code> 

@quickstart_1007_li
#The database URL <code>jdbc:h2:~/test</code> opens the database <code>test</code> in your user home directory 

@quickstart_1008_li
#A new database is automatically created 

@quickstart_1009_h2
H2 コンソール アプリケーション

@quickstart_1010_p
# The Console lets you access a SQL database using a browser interface. 

@quickstart_1011_p
# If you don't have Windows XP, or if something does not work as expected, please see the detailed description in the <a href="tutorial.html">Tutorial</a>. 

@quickstart_1012_h3
手順

@quickstart_1013_h4
インストール

@quickstart_1014_p
# Install the software using the Windows Installer (if you did not yet do that). 

@quickstart_1015_h4
コンソールを起動する

@quickstart_1016_p
# Click [Start], [All Programs], [H2], and [H2 Console (Command Line)]:

@quickstart_1017_p
# A new console window appears:

@quickstart_1018_p
# Also, a new browser page should open with the URL <a href="http://localhost:8082" class="notranslate">http://localhost:8082</a>. You may get a security warning from the firewall. If you don't want other computers in the network to access the database on your machine, you can let the firewall block these connections. Only local connections are required at this time. 

@quickstart_1019_h4
ログイン

@quickstart_1020_p
# Select [Generic H2] and click [Connect]:

@quickstart_1021_p
# You are now logged in. 

@quickstart_1022_h4
サンプル

@quickstart_1023_p
# Click on the [Sample SQL Script]:

@quickstart_1024_p
# The SQL commands appear in the command area.

@quickstart_1025_h4
実行する

@quickstart_1026_p
# Click [Run]

@quickstart_1027_p
# On the left side, a new entry TEST is added below the database icon. The operations and results of the statements are shown below the script.

@quickstart_1028_h4
切断

@quickstart_1029_p
# Click on [Disconnect]:

@quickstart_1030_p
# to close the connection. 

@quickstart_1031_h4
終了

@quickstart_1032_p
# Close the console window. For more information, see the <a href="tutorial.html">Tutorial</a>. 

@roadmap_1000_h1
ロードマップ

@roadmap_1001_p
# New (feature) requests will usually be added at the very end of the list. The priority is increased for important and popular requests. Of course, patches are always welcome, but are not always applied as is. See also <a href="build.html#providing_patches">Providing Patches</a>. 

@roadmap_1002_h2
#Version 1.3.x: Planned Changes

@roadmap_1003_li
#Lob storage: enable the system property h2.lobInDatabase by default. 

@roadmap_1004_li
#Automatic ANALYZE: set the system property h2.analyzeAuto to 2000. 

@roadmap_1005_li
#Enable h2.functionsInSchema. 

@roadmap_1006_h2
#Priority 1

@roadmap_1007_li
#Bugfixes 

@roadmap_1008_li
#Support very large transactions. Reduce memory usage of undo log. 

@roadmap_1009_li
#More tests with MULTI_THREADED=1 

@roadmap_1010_li
#Optimization: result set caching (like MySQL); option to disable 

@roadmap_1011_li
#Server side cursors 

@roadmap_1012_h2
#Priority 2

@roadmap_1013_li
#Improve test code coverage. 

@roadmap_1014_li
#Test multi-threaded in-memory db access 

@roadmap_1015_li
#MVCC: select for update should only lock the selected rows. 

@roadmap_1016_li
#Option to shutdown all the running servers (on the same VM). 

@roadmap_1017_li
#Full outer joins. 

@roadmap_1018_li
#Support nested outer joins (see todo.txt). 

@roadmap_1019_li
#Clustering: support mixed clustering mode (one embedded, others in server mode). 

@roadmap_1020_li
#Clustering: reads should be randomly distributed (optional) or to a designated database on RAM (parameter: READ_FROM=3). 

@roadmap_1021_li
#PostgreSQL catalog: use BEFORE SELECT triggers instead of views over metadata tables. 

@roadmap_1022_li
#Test very large databases and LOBs (up to 256 GB). 

@roadmap_1023_li
#Support hints for the optimizer (which index to use, enforce the join order). 

@roadmap_1024_li
#Sequence: add features [NO] MINVALUE, MAXVALUE, CYCLE. 

@roadmap_1025_li
#Access rights: remember the owner of an object. Create, alter and drop privileges. COMMENT: allow owner of object to change it. 

@roadmap_1026_li
#Deferred integrity checking (DEFERRABLE INITIALLY DEFERRED). 

@roadmap_1027_li
#Groovy Stored Procedures: http://groovy.codehaus.org/Groovy+SQL 

@roadmap_1028_li
#Add a migration guide (list differences between databases). 

@roadmap_1029_li
#Migrate database tool (also from other database engines). 

@roadmap_1030_li
#Optimization: automatic index creation suggestion using the trace file? 

@roadmap_1031_li
#Compression performance: don't allocate buffers, compress / expand in to out buffer. 

@roadmap_1032_li
#Rebuild index functionality to shrink index size and improve performance. 

@roadmap_1033_li
#Don't use deleteOnExit (bug 4513817: File.deleteOnExit consumes memory). 

@roadmap_1034_li
#Console: add accesskey to most important commands (A, AREA, BUTTON, INPUT, LABEL, LEGEND, TEXTAREA). 

@roadmap_1035_li
#Test performance again with SQL Server, Oracle, DB2. 

@roadmap_1036_li
#Test with Spatial DB in a box / JTS: http://www.opengeospatial.org/standards/sfs - OpenGIS Implementation Specification. 

@roadmap_1037_li
#Write more tests and documentation for MVCC (Multi Version Concurrency Control). 

@roadmap_1038_li
#Find a tool to view large text file (larger than 100 MB), with find, page up and down (like less), truncate before / after. 

@roadmap_1039_li
#Implement, test, document XAConnection and so on. 

@roadmap_1040_li
#Pluggable data type (for streaming, hashing, compression, validation, conversion, encryption). 

@roadmap_1041_li
#CHECK: find out what makes CHECK=TRUE slow, move to CHECK2. 

@roadmap_1042_li
#Index usage for (ID, NAME)=(1, 'Hi'); document. 

@roadmap_1043_li
#Make DDL (Data Definition) operations transactional. 

@roadmap_1044_li
#RANK() and DENSE_RANK(), Partition using OVER(). 

@roadmap_1045_li
#Set a connection read only (Connection.setReadOnly) or using a connection parameter. 

@roadmap_1046_li
#Optimizer: use an index for IS NULL and IS NOT NULL (including linked tables). ID IS NOT NULL could be converted to ID &gt;= Integer.MIN_VALUE. 

@roadmap_1047_li
#Access rights: finer grained access control (grant access for specific functions). 

@roadmap_1048_li
#Version check: docs / web console (using Javascript), and maybe in the library (using TCP/IP). 

@roadmap_1049_li
#Web server classloader: override findResource / getResourceFrom. 

@roadmap_1050_li
#Cost for embedded temporary view is calculated wrong, if result is constant. 

@roadmap_1051_li
#Comparison: pluggable sort order: natural sort. 

@roadmap_1052_li
#Count index range query (count(*) where id between 10 and 20). 

@roadmap_1053_li
#Performance: update in-place. 

@roadmap_1054_li
#Recursive Queries (see details). 

@roadmap_1055_li
#Eclipse plugin. 

@roadmap_1056_li
#Asynchronous queries to support publish/subscribe: SELECT ... FOR READ WAIT [maxMillisToWait]. 

@roadmap_1057_li
#Fulltext search Lucene: analyzer configuration. 

@roadmap_1058_li
#Fulltext search (native): reader / tokenizer / filter. 

@roadmap_1059_li
#Linked schema using CSV files: one schema for a directory of files; support indexes for CSV files. 

@roadmap_1060_li
#iReport to support H2. 

@roadmap_1061_li
#Implement missing JDBC API (CallableStatement,...). 

@roadmap_1062_li
#Compression of the cache. 

@roadmap_1063_li
#Include SMPT (mail) client (alert on cluster failure, low disk space,...). 

@roadmap_1064_li
#Drop with restrict (currently cascade is the default). 

@roadmap_1065_li
#JSON parser and functions. 

@roadmap_1066_li
#Server: client ping from time to time (to avoid timeout - is timeout a problem?). 

@roadmap_1067_li
#Copy database: tool with config GUI and batch mode, extensible (example: compare). 

@roadmap_1068_li
#Document, implement tool for long running transactions using user-defined compensation statements. 

@roadmap_1069_li
#Support SET TABLE DUAL READONLY. 

@roadmap_1070_li
#GCJ: what is the state now? 

@roadmap_1071_li
#Events for: database Startup, Connections, Login attempts, Disconnections, Prepare (after parsing), Web Server. See http://docs.openlinksw.com/virtuoso/fn_dbev_startup.html 

@roadmap_1072_li
#Optimization: log compression. 

@roadmap_1073_li
#ROW_NUMBER() OVER([ORDER BY columnName]). 

@roadmap_1074_li
#Support standard INFORMATION_SCHEMA tables, as defined in http://www.contrib.andrew.cmu.edu/~shadow/sql/sql1992.txt - specially KEY_COLUMN_USAGE: http://dev.mysql.com/doc/refman/5.0/en/information-schema.html, http://www.xcdsql.org/Misc/INFORMATION_SCHEMA%20With%20Rolenames.gif 

@roadmap_1075_li
#Compatibility: in MySQL, HSQLDB, /0.0 is NULL; in PostgreSQL, Derby: division by zero. 

@roadmap_1076_li
#Functional tables should accept parameters from other tables (see FunctionMultiReturn) SELECT * FROM TEST T, P2C(T.A, T.R). 

@roadmap_1077_li
#Custom class loader to reload functions on demand. 

@roadmap_1078_li
#Clustering: when a database is back alive, automatically synchronize with the master. 

@roadmap_1079_li
#Test http://mysql-je.sourceforge.net/ 

@roadmap_1080_li
#Performance: automatically build in-memory indexes if the whole table is in memory. 

@roadmap_1081_li
#H2 Console: the webclient could support more features like phpMyAdmin. 

@roadmap_1082_li
#Use Janino to convert Java to C++. 

@roadmap_1083_li
#The HELP information schema can be directly exposed in the Console. 

@roadmap_1084_li
#Maybe use the 0x1234 notation for binary fields, see MS SQL Server. 

@roadmap_1085_li
#Support Oracle CONNECT BY in some way: http://www.adp-gmbh.ch/ora/sql/connect_by.html http://philip.greenspun.com/sql/trees.html 

@roadmap_1086_li
#SQL Server 2005, Oracle: support COUNT(*) OVER(). See http://www.orafusion.com/art_anlytc.htm 

@roadmap_1087_li
#SQL 2003: http://www.wiscorp.com/sql_2003_standard.zip 

@roadmap_1088_li
#Version column (number/sequence and timestamp based). 

@roadmap_1089_li
#Optimize getGeneratedKey: send last identity after each execute (server). 

@roadmap_1090_li
#Test and document UPDATE TEST SET (ID, NAME) = (SELECT ID*10, NAME || '!' FROM TEST T WHERE T.ID=TEST.ID). 

@roadmap_1091_li
#Max memory rows / max undo log size: use block count / row size not row count. 

@roadmap_1092_li
#Support 123L syntax as in Java; example: SELECT (2000000000*2). 

@roadmap_1093_li
#Implement point-in-time recovery. 

@roadmap_1094_li
#LIKE: improved version for larger texts (currently using naive search). 

@roadmap_1095_li
#Automatically convert to the next 'higher' data type whenever there is an overflow. 

@roadmap_1096_li
#Throw an exception when the application calls getInt on a Long (optional). 

@roadmap_1097_li
#Default date format for input and output (local date constants). 

@roadmap_1098_li
#Support custom Collators. 

@roadmap_1099_li
#Document ROWNUM usage for reports: SELECT ROWNUM, * FROM (subquery). 

@roadmap_1100_li
#File system that writes to two file systems (replication, replicating file system). 

@roadmap_1101_li
#Standalone tool to get relevant system properties and add it to the trace output. 

@roadmap_1102_li
#Support 'call proc(1=value)' (PostgreSQL, Oracle). 

@roadmap_1103_li
#Console: improve editing data (Tab, Shift-Tab, Enter, Up, Down, Shift+Del?). 

@roadmap_1104_li
#Console: autocomplete Ctrl+Space inserts template. 

@roadmap_1105_li
#Option to encrypt .trace.db file. 

@roadmap_1106_li
#Write Behind Cache on SATA leads to data corruption See also http://sr5tech.com/write_back_cache_experiments.htm and http://www.jasonbrome.com/blog/archives/2004/04/03/writecache_enabled.html 

@roadmap_1107_li
#Functions with unknown return or parameter data types: serialize / deserialize. 

@roadmap_1108_li
#Auto-Update feature for database, .jar file. 

@roadmap_1109_li
#ResultSet SimpleResultSet.readFromURL(String url): id varchar, state varchar, released timestamp. 

@roadmap_1110_li
#Partial indexing (see PostgreSQL). 

@roadmap_1111_li
#Add GUI to build a custom version (embedded, fulltext,...) using build flags. 

@roadmap_1112_li
#http://rubyforge.org/projects/hypersonic/ 

@roadmap_1113_li
#Add comparator (x === y) : (x = y or (x is null and y is null)). 

@roadmap_1114_li
#Add a sample application that runs the H2 unit test and writes the result to a file (so it can be included in the user app). 

@roadmap_1115_li
#Count on a column that can not be null could be optimized to COUNT(*). 

@roadmap_1116_li
#Table order: ALTER TABLE TEST ORDER BY NAME DESC (MySQL compatibility). 

@roadmap_1117_li
#Issue 159: System property for the H2 Console and TCP configuration (which .h2.server.properties and .h2.keystore to use). 

@roadmap_1118_li
#Backup tool should work with other databases as well. 

@roadmap_1119_li
#Console: -ifExists doesn't work for the console. Add a flag to disable other dbs. 

@roadmap_1120_li
#Check if 'FSUTIL behavior set disablelastaccess 1' improves the performance (fsutil behavior query disablelastaccess). 

@roadmap_1121_li
#Java static code analysis: http://pmd.sourceforge.net/ 

@roadmap_1122_li
#Java static code analysis: http://www.eclipse.org/tptp/ 

@roadmap_1123_li
#Compatibility for CREATE SCHEMA AUTHORIZATION. 

@roadmap_1124_li
#Implement Clob / Blob truncate and the remaining functionality. 

@roadmap_1125_li
#Tree join functionality. 

@roadmap_1126_li
#Add multiple columns at the same time with ALTER TABLE .. ADD .. ADD ... 

@roadmap_1127_li
#Use JDK 1.4 file locking for the database file and for the lock file (but not yet by default); writing a system property to detect concurrent access from the same VM (different classloaders). 

@roadmap_1128_li
#Pure SQL triggers (example: update parent table if the child table is changed). 

@roadmap_1129_li
#Add H2 to Gem (Ruby install system). 

@roadmap_1130_li
#Order conditions inside AND / OR to optimize the performance. 

@roadmap_1131_li
#Support Oracle functions: TRUNC, NVL2, TO_CHAR, TO_DATE, TO_NUMBER. 

@roadmap_1132_li
#Support linked JCR tables 

@roadmap_1133_li
#Read InputStream when executing, as late as possible (maybe only embedded mode). Problem with re-execute. 

@roadmap_1134_li
#Native fulltext search: min word length; store word positions 

@roadmap_1135_li
#Add an option to the SCRIPT command to generate only portable / standard SQL 

@roadmap_1136_li
#Updatable Views (simple cases first) 

@roadmap_1137_li
#Improve create index performance 

@roadmap_1138_li
#Implement more JDBC 4.0 features 

@roadmap_1139_li
#Support TRANSFORM / PIVOT as in MS Access 

@roadmap_1140_li
#SELECT * FROM (VALUES (...), (...), ....) AS alias(f1, ...) 

@roadmap_1141_li
#Support updatable views with join on primary keys (to extend a table) 

@roadmap_1142_li
#Public interface for functions (not public static) 

@roadmap_1143_li
#Support reading the transaction log. 

@roadmap_1144_li
#Eliminate undo log records if stored on disk (just one pointer per block, not per record) 

@roadmap_1145_li
#Feature matrix as in <a href="http://www.inetsoftware.de/products/jdbc/mssql/features/default.asp">i-net software</a>. 

@roadmap_1146_li
#Updatable result set on table without primary key or unique index. 

@roadmap_1147_li
#Use LinkedList instead of ArrayList where applicable. 

@roadmap_1148_li
#Allow execution time prepare for SELECT * FROM CSVREAD(?, 'columnNameString') 

@roadmap_1149_li
#Support % operator (modulo). 

@roadmap_1150_li
#Support JMX: create an MBean for each database and server (support JConsole). See http://thedevcloud.blogspot.com/2008/10/displaying-hsql-database-manager-in.html http://java.sun.com/j2se/1.5.0/docs/api/java/lang/management/ManagementFactory.html#getPlatformMBeanServer() http://java.sun.com/j2se/1.5.0/docs/guide/management/agent.html 

@roadmap_1151_li
#Support nested transactions. 

@roadmap_1152_li
#Add a benchmark for big databases, and one for many users. 

@roadmap_1153_li
#Compression in the result set (repeating values in the same column) over TCP/IP. 

@roadmap_1154_li
#Support curtimestamp (like curtime, curdate). 

@roadmap_1155_li
#Support ANALYZE {TABLE|INDEX} tableName COMPUTE|ESTIMATE|DELETE STATISTICS ptnOption options. 

@roadmap_1156_li
#Release locks (shared or exclusive) on demand 

@roadmap_1157_li
#Support OUTER UNION 

@roadmap_1158_li
#Support parameterized views (similar to CSVREAD, but using just SQL for the definition) 

@roadmap_1159_li
#A way (JDBC driver) to map an URL (jdbc:h2map:c1) to a connection object 

@roadmap_1160_li
#Option for SCRIPT to only process one or a set of tables, and append to a file 

@roadmap_1161_li
#Support linked tables to the current database 

@roadmap_1162_li
#Support dynamic linked schema (automatically adding/updating/removing tables) 

@roadmap_1163_li
#Clustering: adding a node should be very fast and without interrupting clients (very short lock) 

@roadmap_1164_li
#Compatibility with Derby: VALUES(1), (2); SELECT * FROM (VALUES (1), (2)) AS myTable(c1) 

@roadmap_1165_li
#Compatibility: # is the start of a single line comment (MySQL) but date quote (Access). Mode specific 

@roadmap_1166_li
#Run benchmarks with JDK 1.5, JDK 1.6, java -server 

@roadmap_1167_li
#Optimizations: faster hash function for strings, byte arrays 

@roadmap_1168_li
#DatabaseEventListener: callback for all operations (including expected time, RUNSCRIPT) and cancel functionality 

@roadmap_1169_li
#Benchmark: add a graph to show how databases scale (performance/database size) 

@roadmap_1170_li
#Implement a SQLData interface to map your data over to a custom object 

@roadmap_1171_li
#In the MySQL and PostgreSQL mode, use lower case identifiers by default (DatabaseMetaData.storesLowerCaseIdentifiers = true) 

@roadmap_1172_li
#Support multiple directories (on different hard drives) for the same database 

@roadmap_1173_li
#Server protocol: use challenge response authentication, but client sends hash(user+password) encrypted with response 

@roadmap_1174_li
#Support EXEC[UTE] (doesn't return a result set, compatible to MS SQL Server) 

@roadmap_1175_li
#Support native XML data type 

@roadmap_1176_li
#Support triggers with a string property or option: SpringTrigger, OSGITrigger 

@roadmap_1177_li
#Ability to resize the cache array when resizing the cache 

@roadmap_1178_li
#Time based cache writing (one second after writing the log) 

@roadmap_1179_li
#Check state of H2 driver for DDLUtils: https://issues.apache.org/jira/browse/DDLUTILS-185 

@roadmap_1180_li
#Index usage for REGEXP LIKE. 

@roadmap_1181_li
#Compatibility: add a role DBA (like ADMIN). 

@roadmap_1182_li
#Better support multiple processors for in-memory databases. 

@roadmap_1183_li
#Support N'text' 

@roadmap_1184_li
#Support compatibility for jdbc:hsqldb:res: 

@roadmap_1185_li
#Provide an Java SQL builder with standard and H2 syntax 

@roadmap_1186_li
#Trace: write OS, file system, JVM,... when opening the database 

@roadmap_1187_li
#Support indexes for views (probably requires materialized views) 

@roadmap_1188_li
#Document SET SEARCH_PATH, BEGIN, EXECUTE, parameters 

@roadmap_1189_li
#Browser: use Desktop.isDesktopSupported and browse when using JDK 1.6 

@roadmap_1190_li
#Server: use one listener (detect if the request comes from an PG or TCP client) 

@roadmap_1191_li
#Support data type INTERVAL 

@roadmap_1192_li
#Optimize SELECT MIN(ID), MAX(ID), COUNT(*) FROM TEST WHERE ID BETWEEN 100 AND 200 

@roadmap_1193_li
#Sequence: PostgreSQL compatibility (rename, create) http://www.postgresql.org/docs/8.2/static/sql-altersequence.html 

@roadmap_1194_li
#DISTINCT: support large result sets by sorting on all columns (additionally) and then removing duplicates. 

@roadmap_1195_li
#Support a special trigger on all tables to allow building a transaction log reader. 

@roadmap_1196_li
#File system with a background writer thread; test if this is faster 

@roadmap_1197_li
#Better document the source code 

@roadmap_1198_li
#Support select * from dual a left join dual b on b.x=(select max(x) from dual) 

@roadmap_1199_li
#Optimization: don't lock when the database is read-only 

@roadmap_1200_li
#Issue 146: Support merge join. 

@roadmap_1201_li
#Integrate spatial functions from http://geosysin.iict.ch/irstv-trac/wiki/H2spatial/Download 

@roadmap_1202_li
#Cluster: hot deploy (adding a node at runtime) 

@roadmap_1203_li
#Support COSH, SINH, and TANH functions 

@roadmap_1204_li
#Oracle: support DECODE method (convert to CASE WHEN). 

@roadmap_1205_li
#Native search: support "phrase search", wildcard search (* and ?), case-insensitive search, boolean operators, and grouping 

@roadmap_1206_li
#Improve documentation of access rights 

@roadmap_1207_li
#Support ENUM data type (see MySQL, PostgreSQL, MS SQL Server, maybe others) 

@roadmap_1208_li
#Remember the user defined data type (domain) of a column 

@roadmap_1209_li
#Support Jackcess (MS Access databases) 

@roadmap_1210_li
#Built-in methods to write large objects (BLOB and CLOB): FILE_WRITE('test.txt', 'Hello World') 

@roadmap_1211_li
#MVCC: support transactionally consistent backups using SCRIPT 

@roadmap_1212_li
#Improve time to open large databases (see mail 'init time for distributed setup') 

@roadmap_1213_li
#Move Maven 2 repository from hsql.sf.net to h2database.sf.net 

@roadmap_1214_li
#Java 1.5 tool: JdbcUtils.closeSilently(s1, s2,...) 

@roadmap_1215_li
#Javadoc: document design patterns used 

@roadmap_1216_li
#Write an article about SQLInjection (h2/src/docsrc/html/images/SQLInjection.txt) 

@roadmap_1217_li
#Convert SQL-injection-2.txt to html document, include SQLInjection.java sample 

@roadmap_1218_li
#Support OUT parameters in user-defined procedures. 

@roadmap_1219_li
#Web site design: http://www.igniterealtime.org/projects/openfire/index.jsp 

@roadmap_1220_li
#HSQLDB compatibility: Openfire server uses: CREATE SCHEMA PUBLIC AUTHORIZATION DBA; CREATE USER SA PASSWORD ""; GRANT DBA TO SA; SET SCHEMA PUBLIC 

@roadmap_1221_li
#Translation: use ?? in help.csv 

@roadmap_1222_li
#Translated .pdf 

@roadmap_1223_li
#MySQL compatibility: update test1 t1, test2 t2 set t1.id = t2.id where t1.id = t2.id; 

@roadmap_1224_li
#Recovery tool: bad blocks should be converted to INSERT INTO SYSTEM_ERRORS(...), and things should go into the .trace.db file 

@roadmap_1225_li
#RECOVER=2 to backup the database, run recovery, open the database 

@roadmap_1226_li
#Recovery should work with encrypted databases 

@roadmap_1227_li
#Corruption: new error code, add help 

@roadmap_1228_li
#Space reuse: after init, scan all storages and free those that don't belong to a live database object 

@roadmap_1229_li
#Use FilterIn / FilterOut putStream? 

@roadmap_1230_li
#Access rights: add missing features (users should be 'owner' of objects; missing rights for sequences; dropping objects) 

@roadmap_1231_li
#Support NOCACHE table option (Oracle). 

@roadmap_1232_li
#Support table partitioning. 

@roadmap_1233_li
#Index usage for UPDATE ... WHERE .. IN (SELECT...) 

@roadmap_1234_li
#Add regular javadocs (using the default doclet, but another css) to the homepage. 

@roadmap_1235_li
#The database should be kept open for a longer time when using the server mode. 

@roadmap_1236_li
#Javadocs: for each tool, add a copy &amp; paste sample in the class level. 

@roadmap_1237_li
#Javadocs: add @author tags. 

@roadmap_1238_li
#Fluent API for tools: Server.createTcpServer().setPort(9081).setPassword(password).start(); 

@roadmap_1239_li
#MySQL compatibility: real SQL statement for DESCRIBE TEST 

@roadmap_1240_li
#Use a default delay of 1 second before closing a database. 

@roadmap_1241_li
#Write (log) to system table before adding to internal data structures. 

@roadmap_1242_li
#Support very large deletes and updates. 

@roadmap_1243_li
#Doclet (javadocs): constructors are not listed. 

@roadmap_1244_li
#Support direct lookup for MIN and MAX when using WHERE (see todo.txt / Direct Lookup). 

@roadmap_1245_li
#Support other array types (String[], double[]) in PreparedStatement.setObject(int, Object); 

@roadmap_1246_li
#MVCC should not be memory bound (uncommitted data is kept in memory in the delta index; maybe using a regular b-tree index solves the problem). 

@roadmap_1247_li
#Oracle compatibility: support NLS_DATE_FORMAT. 

@roadmap_1248_li
#Cluster: add feature to make sure cluster nodes can not get out of sync (for example by stopping one process). 

@roadmap_1249_li
#H2 Console: support CLOB/BLOB download using a link. 

@roadmap_1250_li
#Support flashback queries as in Oracle. 

@roadmap_1251_li
#Import / Export of fixed with text files. 

@roadmap_1252_li
#Support getGeneratedKeys to return multiple rows when used with batch updates. This is supported by MySQL, but not Derby. Both PostgreSQL and HSQLDB don't support getGeneratedKeys. Also support it when using INSERT ... SELECT. 

@roadmap_1253_li
#HSQLDB compatibility: automatic data type for SUM if value is the value is too big (by default use the same type as the data). 

@roadmap_1254_li
#Improve the optimizer to select the right index for special cases: where id between 2 and 4 and booleanColumn 

@roadmap_1255_li
#Linked tables: make hidden columns available (Oracle: rowid and ora_rowscn columns). 

@roadmap_1256_li
#H2 Console: in-place autocomplete. 

@roadmap_1257_li
#Support large databases: split database files to multiple directories / disks (similar to tablespaces). 

@roadmap_1258_li
#Support to assign a primary key index a user defined name. 

@roadmap_1259_li
#H2 Console: support configuration option for fixed width (monospace) font. 

@roadmap_1260_li
#Native fulltext search: support analyzers (specially for Chinese, Japanese). 

@roadmap_1261_li
#Automatically compact databases from time to time (as a background process). 

@roadmap_1262_li
#Support GRANT SELECT, UPDATE ON *. 

@roadmap_1263_li
#Test Eclipse DTP. 

@roadmap_1264_li
#H2 Console: autocomplete: keep the previous setting 

@roadmap_1265_li
#MySQL, MS SQL Server compatibility: support case sensitive (mixed case) identifiers without quotes. 

@roadmap_1266_li
#executeBatch: option to stop at the first failed statement. 

@roadmap_1267_li
#Implement OLAP features as described here: http://www.devx.com/getHelpOn/10MinuteSolution/16573/0/page/5 

@roadmap_1268_li
#Support Oracle ROWID (unique identifier for each row). 

@roadmap_1269_li
#Server mode: improve performance for batch updates. 

@roadmap_1270_li
#Applets: support read-only databases in a zip file (accessed as a resource). 

@roadmap_1271_li
#Long running queries / errors / trace system table. 

@roadmap_1272_li
#H2 Console should support JaQu directly. 

@roadmap_1273_li
#H2 Console: support single file upload and directory download (optional). 

@roadmap_1274_li
#Document FTL_SEARCH, FTL_SEARCH_DATA. 

@roadmap_1275_li
#Sequences: CURRVAL should be session specific. Compatibility with PostgreSQL. 

@roadmap_1276_li
#Support DatabaseMetaData.insertsAreDetected: updatable result sets should detect inserts. 

@roadmap_1277_li
#Auto-server: add option to define the IP address range or list. 

@roadmap_1278_li
#Index creation using deterministic functions. 

@roadmap_1279_li
#Support DELETE with TOP or LIMIT. See also: http://dev.mysql.com/doc/refman/5.1/de/delete.html 

@roadmap_1280_li
#ANALYZE: for unique indexes that allow null, count the number of null. 

@roadmap_1281_li
#AUTO_SERVER: support changing IP addresses (disable a network while the database is open). 

@roadmap_1282_li
#Avoid using java.util.Calendar internally because it's slow, complicated, and buggy. 

@roadmap_1283_li
#Support TRUNCATE .. CASCADE like PostgreSQL. 

@roadmap_1284_li
#Support opening a database that is in the classpath, maybe using a new file system. 

@roadmap_1285_li
#Fulltext search: lazy result generation using SimpleRowSource. 

@roadmap_1286_li
#Support transformation to join for user defined functions, as for IN(SELECT...). 

@roadmap_1287_li
#Fulltext search: support alternative syntax: WHERE FTL_CONTAINS(name, 'hello'). 

@roadmap_1288_li
#MySQL compatibility: support REPLACE, see http://dev.mysql.com/doc/refman/5.1/de/replace.html 

@roadmap_1289_li
#MySQL compatibility: support INSERT INTO table SET column1 = value1, column2 = value2 

@roadmap_1290_li
#Docs: add a one line description for each functions and SQL statements at the top (in the link section). 

@roadmap_1291_li
#Javadoc search: weight for titles should be higher ('random' should list Functions as the best match). 

@roadmap_1292_li
#Replace information_schema tables with regular tables that are automatically re-built when needed. Use indexes. 

@roadmap_1293_li
#Delete temporary files or objects using finalize. 

@roadmap_1294_li
#Oracle compatibility: support calling 0-parameters functions without parenthesis. Make constants obsolete. 

@roadmap_1295_li
#MySQL, HSQLDB compatibility: support where 'a'=1 (not supported by Derby, PostgreSQL) 

@roadmap_1296_li
#Allow calling function with no parameters without parenthesis. See http://code.google.com/p/h2database/issues/detail?id=50 

@roadmap_1297_li
#CSV: currently # is a line comment and can start at any field. Make it optional. 

@roadmap_1298_li
#Finer granularity for SLF4J trace - See http://code.google.com/p/h2database/issues/detail?id=62 

@roadmap_1299_li
#Add database creation date and time to the database. 

@roadmap_1300_li
#Support ASSERTIONS. 

@roadmap_1301_li
#Support multi-threaded kernel with multi-version concurrency. 

@roadmap_1302_li
#MySQL compatibility: support comparing 1='a' 

@roadmap_1303_li
#Support PostgreSQL lock modes: http://www.postgresql.org/docs/8.3/static/explicit-locking.html 

@roadmap_1304_li
#PostgreSQL compatibility: test DbVisualizer and Squirrel SQL using a new PostgreSQL JDBC driver. 

@roadmap_1305_li
#RunScript should be able to read from system in (or quite mode for Shell). 

@roadmap_1306_li
#Natural join: support select x from dual natural join dual. 

@roadmap_1307_li
#Natural join: somehow support this: select a.x, b.x, x from dual a natural join dual b 

@roadmap_1308_li
#Use the Java service provider mechanism to register file systems and function libraries. 

@roadmap_1309_li
#MySQL compatibility: for auto_increment columns, convert 0 to next value (as when inserting NULL). 

@roadmap_1310_li
#Optimization for multi-column IN: use an index if possible. Example: (A, B) IN((1, 2), (2, 3)). 

@roadmap_1311_li
#Optimization for EXISTS: convert to inner join or IN(..) if possible. 

@roadmap_1312_li
#Functions: support hashcode(value); cryptographic and fast 

@roadmap_1313_li
#Serialized file lock: support long running queries. 

@roadmap_1314_li
#Network: use 127.0.0.1 if other addresses don't work. 

@roadmap_1315_li
#Pluggable network protocol (currently Socket/ServerSocket over TCP/IP) - see also TransportServer with master slave replication. 

@roadmap_1316_li
#Select for update in mvcc mode: only lock the selected records. 

@roadmap_1317_li
#Support reading JCR data: one table per node type; query table; cache option 

@roadmap_1318_li
#OSGi: create a sample application, test, document. 

@roadmap_1319_li
#help.csv: use complete examples for functions; run as test case. 

@roadmap_1320_li
#Functions to calculate the memory and disk space usage of a table, a row, or a value. 

@roadmap_1321_li
#Re-implement PooledConnection; use a lightweight connection object. 

@roadmap_1322_li
#Doclet: convert tests in javadocs to a java class. 

@roadmap_1323_li
#Doclet: format fields like methods, but support sorting by name and value. 

@roadmap_1324_li
#Doclet: shrink the html files. 

@roadmap_1325_li
#MySQL compatibility: support REPLACE - See http://code.google.com/p/h2database/issues/detail?id=73 

@roadmap_1326_li
#MySQL compatibility: support SET NAMES 'latin1' - See also http://code.google.com/p/h2database/issues/detail?id=56 

@roadmap_1327_li
#MySQL compatibility: DELETE .. FROM .. USING - See http://dev.mysql.com/doc/refman/5.0/en/delete.html 

@roadmap_1328_li
#Allow to scan index backwards starting with a value (to better support ORDER BY DESC). 

@roadmap_1329_li
#Java Service Wrapper: try http://yajsw.sourceforge.net/ 

@roadmap_1330_li
#Batch parameter for INSERT, UPDATE, and DELETE, and commit after each batch. See also MySQL DELETE. 

@roadmap_1331_li
#MySQL compatibility: support ALTER TABLE .. MODIFY COLUMN. 

@roadmap_1332_li
#Use a lazy and auto-close input stream (open resource when reading, close on eof). 

@roadmap_1333_li
#PostgreSQL compatibility: generate_series. 

@roadmap_1334_li
#Connection pool: 'reset session' command (delete temp tables, rollback, autocommit true). 

@roadmap_1335_li
#Improve SQL documentation, see http://www.w3schools.com/sql/ 

@roadmap_1336_li
#MySQL compatibility: DatabaseMetaData.stores*() methods should return the same values. Test with SquirrelSQL. 

@roadmap_1337_li
#MS SQL Server compatibility: support DATEPART syntax. 

@roadmap_1338_li
#Oracle compatibility: support CREATE OR REPLACE VIEW syntax. 

@roadmap_1339_li
#Sybase/DB2/Oracle compatibility: support out parameters in stored procedures - See http://code.google.com/p/h2database/issues/detail?id=83 

@roadmap_1340_li
#Support INTERVAL data type (see Oracle and others). 

@roadmap_1341_li
#Combine Server and Console tool (only keep Server). 

@roadmap_1342_li
#Store the Lucene index in the database itself. 

@roadmap_1343_li
#Support standard MERGE statement: http://en.wikipedia.org/wiki/Merge_%28SQL%29 

@roadmap_1344_li
#Oracle compatibility: support DECODE(x, ...). 

@roadmap_1345_li
#Console: Start Browser: if ip number changed, try localhost instead. 

@roadmap_1346_li
#MVCC: compare concurrent update behavior with PostgreSQL and Oracle. 

@roadmap_1347_li
#HSQLDB compatibility: CREATE FUNCTION (maybe using a Function interface). 

@roadmap_1348_li
#HSQLDB compatibility: support CALL "java.lang.Math.sqrt"(2.0) 

@roadmap_1349_li
#Support comma as the decimal separator in the CSV tool. 

@roadmap_1350_li
#Compatibility: Support jdbc:default:connection using ThreadLocal (part of SQLJ) 

@roadmap_1351_li
#Compatibility: Java functions with SQLJ Part1 http://www.acm.org/sigmod/record/issues/9912/standards.pdf.gz 

@roadmap_1352_li
#Compatibility: Java functions with SQL/PSM (Persistent Stored Modules) - need to find the documentation. 

@roadmap_1353_li
#CACHE_SIZE: automatically use a fraction of Runtime.maxMemory - maybe automatically the second level cache. 

@roadmap_1354_li
#Support date/time/timestamp as documented in http://en.wikipedia.org/wiki/ISO_8601 

@roadmap_1355_li
#PostgreSQL compatibility: when in PG mode, treat BYTEA data like PG. 

@roadmap_1356_li
#MySQL compatibility: REPLACE http://dev.mysql.com/doc/refman/6.0/en/replace.html 

@roadmap_1357_li
#Support =ANY(array) as in PostgreSQL. See also http://www.postgresql.org/docs/8.0/interactive/arrays.html 

@roadmap_1358_li
#IBM DB2 compatibility: support PREVIOUS VALUE FOR sequence. 

@roadmap_1359_li
#MySQL compatibility: alter table add index i(c), add constraint c foreign key(c) references t(c); 

@roadmap_1360_li
#Compatibility: use different LIKE ESCAPE characters depending on the mode (disable for Derby, HSQLDB, DB2, Oracle, MSSQLServer). 

@roadmap_1361_li
#Oracle compatibility: support CREATE SYNONYM table FOR schema.table. 

@roadmap_1362_li
#Optimize A=? OR B=? to UNION if the cost is lower. 

@roadmap_1363_li
#FTP: document the server, including -ftpTask option to execute / kill remote processes 

@roadmap_1364_li
#FTP: problems with multithreading? 

@roadmap_1365_li
#FTP: implement SFTP / FTPS 

@roadmap_1366_li
#FTP: access to a database (.csv for a table, a directory for a schema, a file for a lob, a script.sql file). 

@roadmap_1367_li
#More secure default configuration if remote access is enabled. 

@roadmap_1368_li
#Improve database file locking (maybe use native file locking). The current approach seems to be problematic if the file system is on a remote share (see Google Group 'Lock file modification time is in the future'). 

@roadmap_1369_li
#Document internal features such as BELONGS_TO_TABLE, NULL_TO_DEFAULT, SEQUENCE. 

@roadmap_1370_li
#Issue 107: Prefer using the ORDER BY index if LIMIT is used. 

@roadmap_1371_li
#An index on (id, name) should be used for a query: select * from t where s=? order by i 

@roadmap_1372_li
#Support reading sequences using DatabaseMetaData.getTables(null, null, null, new String[]{"SEQUENCE"}). See PostgreSQL. 

@roadmap_1373_li
#Add option to enable TCP_NODELAY using Socket.setTcpNoDelay(true). 

@roadmap_1374_li
#Maybe disallow = within database names (jdbc:h2:mem:MODE=DB2 means database name MODE=DB2). 

@roadmap_1375_li
#Fast alter table add column. 

@roadmap_1376_li
#Improve concurrency for in-memory database operations. 

@roadmap_1377_li
#Issue 122: Support for connection aliases for remote tcp connections. 

@roadmap_1378_li
#Fast scrambling (strong encryption doesn't help if the password is included in the application). 

@roadmap_1379_li
#Support using system properties in database URLs (may be a security problem). 

@roadmap_1380_li
#Issue 126: The index name should be "IDX_" plus the constraint name unless there is a conflict, in which case append a number. 

@roadmap_1381_li
#Issue 127: Support activation/deactivation of triggers 

@roadmap_1382_li
#Issue 130: Custom log event listeners 

@roadmap_1383_li
#Issue 131: IBM DB2 compatibility: sysibm.sysdummy1 

@roadmap_1384_li
#Issue 132: Use Java enum trigger type. 

@roadmap_1385_li
#Issue 134: IBM DB2 compatibility: session global variables. 

@roadmap_1386_li
#Cluster: support load balance with values for each server / auto detect. 

@roadmap_1387_li
#FTL_SET_OPTION(keyString, valueString) with key stopWords at first. 

@roadmap_1388_li
#Pluggable access control mechanism. 

@roadmap_1389_li
#Fulltext search (Lucene): support streaming CLOB data. 

@roadmap_1390_li
#Document/example how to create and read an encrypted script file. 

@roadmap_1391_li
#Check state of https://issues.apache.org/jira/browse/OPENJPA-1367 (H2 does support cross joins). 

@roadmap_1392_li
#Fulltext search (Lucene): only prefix column names with _ if they already start with _. Instead of DATA / QUERY / modified use _DATA, _QUERY, _MODIFIED if possible. 

@roadmap_1393_li
#Support a way to create or read compressed encrypted script files using an API. 

@roadmap_1394_li
#Scripting language support (Javascript). 

@roadmap_1395_li
#The network client should better detect if the server is not an H2 server and fail early. 

@roadmap_1396_li
#H2 Console: support CLOB/BLOB upload. 

@roadmap_1397_li
#Move away from system properties where possible. 

@roadmap_1398_li
#Database file lock: detect hibernate / standby / very slow threads (compare system time). 

@roadmap_1399_li
#Automatic detection of redundant indexes. 

@roadmap_1400_li
#Maybe reject join without "on" (except natural join). 

@roadmap_1401_li
#Implement GiST (Generalized Search Tree for Secondary Storage). 

@roadmap_1402_li
#Function to read a number of bytes/characters from an BLOB or CLOB. 

@roadmap_1403_li
#Issue 156: Support SELECT ? UNION SELECT ?. 

@roadmap_1404_li
#Automatic mixed mode: support a port range list (to avoid firewall problems). 

@roadmap_1405_li
#Support the pseudo column rowid, oid, _rowid_. 

@roadmap_1406_li
#H2 Console / large result sets: stream early instead of keeping a whole result in-memory 

@roadmap_1407_li
#Support TRUNCATE for linked tables. 

@roadmap_1408_li
#UNION: evaluate INTERSECT before UNION (like most other database except Oracle). 

@roadmap_1409_li
#Delay creating the information schema, and share metadata columns. 

@roadmap_1410_li
#TCP Server: use a nonce (number used once) to protect unencrypted channels against replay attacks. 

@roadmap_1411_li
#Simplify running scripts and recovery: CREATE FORCE USER (overwrites an existing user). 

@roadmap_1412_li
#Support CREATE DATABASE LINK (a custom JDBC driver is already supported). 

@roadmap_1413_li
#Issue 163: Allow to create foreign keys on metadata types. 

@roadmap_1414_li
#Logback: write a native DBAppender. 

@roadmap_1415_li
#Cache size: don't use more cache than what is available. 

@roadmap_1416_li
#Tree index: Instead of an AVL tree, use a general balanced trees or a scapegoat tree. 

@roadmap_1417_li
#User defined functions: allow to store the bytecode (of just the class, or the jar file of the extension) in the database. 

@roadmap_1418_li
#Compatibility: ResultSet.getObject() on a CLOB (TEXT) should return String for PostgreSQL and MySQL. 

@roadmap_1419_li
#Optimizer: WHERE X=? AND Y IN(?), it always uses the index on Y. Should be cost based. 

@roadmap_1420_li
#Support ALTER SCHEMA name RENAME TO newName (rename schema). 

@roadmap_1421_li
#Make the cache scan resistant (currently a small cache is faster than a large cache for large table scans). 

@roadmap_1422_li
#Issue 178: Optimizer: index usage when both ascending and descending indexes are available 

@roadmap_1423_li
#Issue 179: Related subqueries in HAVING clause 

@roadmap_1424_li
#IBM DB2 compatibility: NOT NULL WITH DEFAULT. Similar to MySQL Mode.convertInsertNullToZero. 

@roadmap_1425_li
#Creating primary key: always create a constraint. 

@roadmap_1426_li
#Support a data type "timestamp with timezone" using java.util.Calendar. 

@roadmap_1427_li
#Maybe use a different page layout: keep the data at the head of the page, and ignore the tail (don't store / read it). This may increase write / read performance depending on the file system. 

@roadmap_1428_li
#Indexes of temporary tables are currently kept in-memory. Is this how it should be? 

@roadmap_1429_li
#The Shell tool should support the same built-in commands as the H2 Console. 

@roadmap_1430_li
#Maybe use PhantomReference instead of finalize. 

@roadmap_1431_li
#Database file name suffix: a way to use no or a different suffix (for example using a slash). 

@roadmap_1432_li
#Database file name suffix: should only have one dot by default. Example: .h2db 

@roadmap_1433_li
#Issue 196: Function based indexes 

@roadmap_1434_h2
#Not Planned

@roadmap_1435_li
#HSQLDB (did) support this: select id i from test where i&lt;0 (other databases don't). Supporting it may break compatibility. 

@roadmap_1436_li
#String.intern (so that Strings can be compared with ==) will not be used because some VMs have problems when used extensively. 

@roadmap_1437_li
#In prepared statements, identifier names (table names and so on) can not be parameterized. Adding such a feature would complicate the source code without providing reasonable speedup, and would slow down regular prepared statements. 

@sourceError_1000_h1
#Error Analyzer

@sourceError_1001_a
ホーム

@sourceError_1002_a
#Input

@sourceError_1003_h2
#&nbsp; <a href="javascript:select('details')" id = "detailsTab">Details</a>&nbsp; <a href="javascript:select('source')" id = "sourceTab">Source Code</a> 

@sourceError_1004_p
#Paste the error message and stack trace below and click on 'Details' or 'Source Code': 

@sourceError_1005_b
#Error Code: 

@sourceError_1006_b
#Product Version: 

@sourceError_1007_b
#Message: 

@sourceError_1008_b
#More Information:

@sourceError_1009_b
#Stack Trace: 

@sourceError_1010_b
#Source File: 

@sourceError_1011_p
# Raw file 

@sourceError_1012_p
# (fast; only Firefox)

@tutorial_1000_h1
チュートリアル

@tutorial_1001_a
# Starting and Using the H2 Console

@tutorial_1002_a
# Special H2 Console Syntax

@tutorial_1003_a
# Settings of the H2 Console

@tutorial_1004_a
# Connecting to a Database using JDBC

@tutorial_1005_a
# Creating New Databases

@tutorial_1006_a
# Using the Server

@tutorial_1007_a
# Using Hibernate

@tutorial_1008_a
# Using TopLink and Glassfish

@tutorial_1009_a
# Using EclipseLink

@tutorial_1010_a
# Using Databases in Web Applications

@tutorial_1011_a
# CSV (Comma Separated Values) Support

@tutorial_1012_a
# Upgrade, Backup, and Restore

@tutorial_1013_a
# Command Line Tools

@tutorial_1014_a
# The Shell Tool

@tutorial_1015_a
# Using OpenOffice Base

@tutorial_1016_a
# Java Web Start / JNLP

@tutorial_1017_a
# Using a Connection Pool

@tutorial_1018_a
# Fulltext Search

@tutorial_1019_a
# User-Defined Variables

@tutorial_1020_a
# Date and Time

@tutorial_1021_a
# Using Spring

@tutorial_1022_h2
起動とH2コンソールの使用

@tutorial_1023_p
# The H2 Console application lets you access a SQL database using a browser interface. This can be a H2 database, or another database that supports the JDBC API. 

@tutorial_1024_p
# This is a client / server application, so both a server and a client (a browser) are required to run it. 

@tutorial_1025_p
# Depending on your platform and environment, there are multiple ways to start the application: 

@tutorial_1026_th
OS

@tutorial_1027_th
起動

@tutorial_1028_td
Windows

@tutorial_1029_td
# Click [Start], [All Programs], [H2], and [H2 Console (Command Line)]

@tutorial_1030_td
# When using the Sun JDK 1.5, a window with the title 'H2 Console ' should appear. When using the Sun JDK 1.6, an icon will be added to the system tray: 

@tutorial_1031_td
# If you don't get the window and the system tray icon, then maybe Java is not installed correctly (in this case, try another way to start the application). A browser window should open and point to the Login page at <code>http://localhost:8082</code>. 

@tutorial_1032_td
Windows

@tutorial_1033_td
# Open a file browser, navigate to <code>h2/bin</code>, and double click on <code>h2.bat</code>.

@tutorial_1034_td
# A console window appears. If there is a problem, you will see an error message in this window. A browser window will open and point to the Login page (URL: <code>http://localhost:8082</code>). 

@tutorial_1035_td
Any

@tutorial_1036_td
# Double click on the <code>h2*.jar</code> file. This only works if the <code>.jar</code> suffix is associated with java. 

@tutorial_1037_td
Any

@tutorial_1038_td
# Open a console window, navigate to the directory <code>h2/bin</code> and type: 

@tutorial_1039_h3
ファイアウォール

@tutorial_1040_p
# If you start the server, you may get a security warning from the firewall (if you have installed one). If you don't want other computers in the network to access the application on your machine, you can let the firewall block those connections. The connection from the local machine will still work. Only if you want other computers to access the database on this computer, you need allow remote connections in the firewall. 

@tutorial_1041_p
# It has been reported that when using Kaspersky 7.0 with firewall, the H2 Console is very slow when connecting over the IP address. A workaround is to connect using localhost, however this only works on the local machine. 

@tutorial_1042_p
# A small firewall is already built into the server: other computers may not connect to the server by default. To change this, go to 'Preferences' and select 'Allow connections from other computers'. 

@tutorial_1043_h3
Javaをテストする

@tutorial_1044_p
# To find out which version of Java is installed, open a command prompt and type: 

@tutorial_1045_p
# If you get an error message, you may need to add the Java binary directory to the path environment variable. 

@tutorial_1046_h3
#Error Message 'Port may be in use'

@tutorial_1047_p
# You can only start one instance of the H2 Console, otherwise you will get the following error message: "The Web server could not be started. Possible cause: another server is already running...". It is possible to start multiple console applications on the same computer (using different ports), but this is usually not required as the console supports multiple concurrent connections. 

@tutorial_1048_h3
他のポートを使用する

@tutorial_1049_p
# If the port is in use by another application, you may want to start the H2 Console on a different port. This can be done by changing the port in the file <code>.h2.server.properties</code>. This file is stored in the user directory (for Windows, this is usually in <code>Documents and Settings/&lt;username&gt;</code>). The relevant entry is webPort. 

@tutorial_1050_h3
ブラウザを使用してサーバーに接続

@tutorial_1051_p
# If the server started successfully, you can connect to it using a web browser. JavaScript needs to be enabled. If you started the server on the same computer as the browser, open the URL <code>http://localhost:8082</code>. If you want to connect to the application from another computer, you need to provide the IP address of the server, for example: <code>http://192.168.0.2:8082</code>. If you enabled SSL on the server side, the URL needs to start with <code>https://</code>. 

@tutorial_1052_h3
複数の同時セッション

@tutorial_1053_p
# Multiple concurrent browser sessions are supported. As that the database objects reside on the server, the amount of concurrent work is limited by the memory available to the server application. 

@tutorial_1054_h3
ログイン

@tutorial_1055_p
# At the login page, you need to provide connection information to connect to a database. Set the JDBC driver class of your database, the JDBC URL, user name and password. If you are done, click [Connect]. 

@tutorial_1056_p
# You can save and reuse previously saved settings. The settings are stored in a properties file (see <a href="#console_settings">Settings of the H2 Console</a>). 

@tutorial_1057_h3
エラーメッセージ

@tutorial_1058_p
# Error messages in are shown in red. You can show/hide the stack trace of the exception by clicking on the message. 

@tutorial_1059_h3
データベースドライバの追加

@tutorial_1060_p
# Additional database drivers to connect to other databases (MySQL, PostgreSQL, HSQLDB,...) can be registered by adding the Jar file location of the driver to the environment variables <code>H2DRIVERS</code> or <code>CLASSPATH</code>. Example (Windows): to add the database driver library <code>C:\Programs\hsqldb\lib\hsqldb.jar</code>, set the environment variable <code>H2DRIVERS</code> to <code>C:\Programs\hsqldb\lib\hsqldb.jar</code>. 

@tutorial_1061_p
# Multiple drivers can be set; each entry needs to be separated with a <code>;</code> (Windows) or <code>:</code> (other operating systems). Spaces in the path names are supported. The settings must not be quoted. 

@tutorial_1062_h3
#Using the H2 Console

@tutorial_1063_p
# The H2 Console application has three main panels: the toolbar on top, the tree on the left, and the query / result panel on the right. The database objects (for example, tables) are listed on the left panel. Type in a SQL command on the query panel and click 'Run'. The result of the command appears just below the command. 

@tutorial_1064_h3
テーブル名、またはカラム名をインサートする

@tutorial_1065_p
# The table name and column names can be inserted in the script by clicking them in the tree. If you click on a table while the query is empty, then <code>SELECT * FROM ...</code> is added as well. While typing a query, the table that was used is automatically expanded in the tree. For example if you type <code>SELECT * FROM TEST T WHERE T.</code> then the table TEST is automatically expanded in the tree. 

@tutorial_1066_h3
切断とアプリケーションの終了

@tutorial_1067_p
# To log out of the database, click 'Disconnect' in the toolbar panel. However, the server is still running and ready to accept new sessions. 

@tutorial_1068_p
# To stop the server, right click on the system tray icon and select [Exit]. If you don't have the system tray icon, navigate to [Preferences] and click [Shutdown], press [Ctrl]+[C] in the console where the server was started (Windows), or close the console window. 

@tutorial_1069_h2
#Special H2 Console Syntax

@tutorial_1070_p
# The H2 Console supports a few built-in commands. Those are interpreted within the H2 Console, that means they work with any database. They need to be at the beginning of a statement (before any remarks), otherwise they are not parsed correctly. If in doubt, add ';' before the command. 

@tutorial_1071_th
#Command(s)

@tutorial_1072_th
説明

@tutorial_1073_td
# @autocommit_true;

@tutorial_1074_td
# @autocommit_false; 

@tutorial_1075_td
# Enable or disable autocommit. 

@tutorial_1076_td
# @cancel; 

@tutorial_1077_td
# Cancel the currently running statement. 

@tutorial_1078_td
# @columns null null TEST;

@tutorial_1079_td
# @index_info&nbsp;null&nbsp;null&nbsp;TEST;

@tutorial_1080_td
# @tables;

@tutorial_1081_td
# @tables null null TEST;

@tutorial_1082_td
# Call the corresponding DatabaseMetaData.get method. Patterns are case sensitive (usually identifiers are uppercase). For information about the parameters, see the Javadoc documentation. Missing parameters at the end are set to null. The complete list of commands is: <code> @attributes @best_row_identifier @catalogs @columns @column_privileges @cross_references @exported_keys @imported_keys @index_info @primary_keys @procedures @procedure_columns @schemas @super_tables @super_types @tables @table_privileges @table_types @type_info @udts @version_columns </code> 

@tutorial_1083_td
# @edit select * from test; 

@tutorial_1084_td
# Use an updatable result set. 

@tutorial_1085_td
# @generated&nbsp;insert&nbsp;into&nbsp;test()&nbsp;values(); 

@tutorial_1086_td
# Show the result of <code>Statement.getGeneratedKeys()</code>. 

@tutorial_1087_td
# @history; 

@tutorial_1088_td
# Show the command history. 

@tutorial_1089_td
# @info; 

@tutorial_1090_td
# Display the result of various <code>Connection</code> and <code>DatabaseMetaData</code> methods. 

@tutorial_1091_td
# @list select * from test; 

@tutorial_1092_td
# Show the result set in list format (each column on its own line, with row numbers). 

@tutorial_1093_td
# @loop 1000 select ?, ?/*rnd*/;

@tutorial_1094_td
# @loop 1000 @statement select ?; 

@tutorial_1095_td
# Run the statement this many times. Parameters (<code>?</code>) are set using a loop from 0 up to x - 1. Random values are used for each <code>?/*rnd*/</code>. A Statement object is used instead of a PreparedStatement if <code>@statement</code> is used. Result sets are read until <code>ResultSet.next()</code> returns <code>false</code>. Timing information is printed. 

@tutorial_1096_td
# @maxrows&nbsp;20; 

@tutorial_1097_td
# Set the maximum number of rows to display. 

@tutorial_1098_td
# @memory; 

@tutorial_1099_td
# Show the used and free memory. This will call <code>System.gc()</code>. 

@tutorial_1100_td
# @meta&nbsp;select&nbsp;1; 

@tutorial_1101_td
# List the <code>ResultSetMetaData</code> after running the query. 

@tutorial_1102_td
# @parameter_meta&nbsp;select&nbsp;?; 

@tutorial_1103_td
# Show the result of the <code>PreparedStatement.getParameterMetaData()</code> calls. The statement is not executed. 

@tutorial_1104_td
# @prof_start;

@tutorial_1105_td
# call&nbsp;hash('SHA256',&nbsp;'',&nbsp;1000000);

@tutorial_1106_td
# @prof_stop; 

@tutorial_1107_td
# Start / stop the built-in profiling tool. The top 3 stack traces of the statement(s) between start and stop are listed (if there are 3). 

@tutorial_1108_td
# @transaction_isolation;

@tutorial_1109_td
# @transaction_isolation&nbsp;2; 

@tutorial_1110_td
# Display (without parameters) or change (with parameters 1, 2, 4, 8) the transaction isolation level. 

@tutorial_1111_h2
#Settings of the H2 Console

@tutorial_1112_p
# The settings of the H2 Console are stored in a configuration file called <code>.h2.server.properties</code> in you user home directory. For Windows installations, the user home directory is usually <code>C:\Documents and Settings\[username]</code>. The configuration file contains the settings of the application and is automatically created when the H2 Console is first started. 

@tutorial_1113_h2
JDBCを使用してデータベースに接続

@tutorial_1114_p
# To connect to a database, a Java application first needs to load the database driver, and then get a connection. A simple way to do that is using the following code: 

@tutorial_1115_p
# This code first loads the driver (<code>Class.forName(...)</code>) and then opens a connection (using <code>DriverManager.getConnection()</code>). The driver name is <code>"org.h2.Driver"</code>. The database URL always needs to start with <code>jdbc:h2:</code> to be recognized by this database. The second parameter in the <code>getConnection()</code> call is the user name (<code>sa</code> for System Administrator in this example). The third parameter is the password. In this database, user names are not case sensitive, but passwords are. 

@tutorial_1116_h2
新しいデータベースを作成する

@tutorial_1117_p
# By default, if the database specified in the URL does not yet exist, a new (empty) database is created automatically. The user that created the database automatically becomes the administrator of this database. 

@tutorial_1118_p
# Auto-creating new database can be disabled, see <a href="features.html#database_only_if_exists">Opening a Database Only if it Already Exists</a>. 

@tutorial_1119_h2
サーバーを使用する

@tutorial_1120_p
# H2 currently supports three server: a web server (for the H2 Console), a TCP server (for client/server connections) and an PG server (for PostgreSQL clients). The servers can be started in different ways, one is using the <code>Server</code> tool. 

@tutorial_1121_h3
#Starting the Server Tool from Command Line

@tutorial_1122_p
# To start the <code>Server</code> tool from the command line with the default settings, run: 

@tutorial_1123_p
# This will start the tool with the default options. To get the list of options and default values, run: 

@tutorial_1124_p
# There are options available to use other ports, and start or not start parts. 

@tutorial_1125_h3
TCPサーバーに接続する

@tutorial_1126_p
# To remotely connect to a database using the TCP server, use the following driver and database URL: 

@tutorial_1127_li
#JDBC driver class: <code>org.h2.Driver</code> 

@tutorial_1128_li
#Database URL: <code>jdbc:h2:tcp://localhost/~/test</code> 

@tutorial_1129_p
# For details about the database URL, see also in Features. 

@tutorial_1130_h3
#Starting the TCP Server within an Application

@tutorial_1131_p
# Servers can also be started and stopped from within an application. Sample code: 

@tutorial_1132_h3
他の過程からTCPサーバーを終了する

@tutorial_1133_p
# The TCP server can be stopped from another process. To stop the server from the command line, run: 

@tutorial_1134_p
# To stop the server from a user application, use the following code: 

@tutorial_1135_p
# This function will only stop the TCP server. If other server were started in the same process, they will continue to run. To avoid recovery when the databases are opened the next time, all connections to the databases should be closed before calling this method. To stop a remote server, remote connections must be enabled on the server. Shutting down a TCP server can be protected using the option <code>-tcpPassword</code> (the same password must be used to start and stop the TCP server). 

@tutorial_1136_h2
Hibernateを使用する

@tutorial_1137_p
# This database supports Hibernate version 3.1 and newer. You can use the HSQLDB Dialect, or the native H2 Dialect. Unfortunately the H2 Dialect included in some versions of Hibernate is buggy. A <a href="http://opensource.atlassian.com/projects/hibernate/browse/HHH-3401">patch for Hibernate</a> has been submitted and is now applied. The dialect for the newest version of Hibernate is also available at <code>src/tools/org/hibernate/dialect/H2Dialect.java.txt</code>. You can rename it to <code>H2Dialect.java</code> and include this as a patch in your application, or upgrade to a version of Hibernate where this is fixed. 

@tutorial_1138_h2
#Using TopLink and Glassfish

@tutorial_1139_p
# To use H2 with Glassfish (or Sun AS), set the Datasource Classname to <code>org.h2.jdbcx.JdbcDataSource</code>. You can set this in the GUI at Application Server - Resources - JDBC - Connection Pools, or by editing the file <code>sun-resources.xml</code>: at element <code>jdbc-connection-pool</code>, set the attribute <code>datasource-classname</code> to <code>org.h2.jdbcx.JdbcDataSource</code>. 

@tutorial_1140_p
# The H2 database is compatible with HSQLDB and PostgreSQL. To take advantage of H2 specific features, use the <code>H2Platform</code>. The source code of this platform is included in H2 at <code>src/tools/oracle/toplink/essentials/platform/database/DatabasePlatform.java.txt</code>. You will need to copy this file to your application, and rename it to .java. To enable it, change the following setting in persistence.xml: 

@tutorial_1141_p
# In old versions of Glassfish, the property name is <code>toplink.platform.class.name</code>. 

@tutorial_1142_h2
#Using EclipseLink

@tutorial_1143_p
# To use H2 in EclipseLink, use the platform class <code>org.eclipse.persistence.platform.database.H2Platform</code>. If this platform is not available in your version of EclipseLink, you can use the OraclePlatform instead in many case. See also <a href="http://wiki.eclipse.org/EclipseLink/Development/Incubator/Extensions/H2Platform">H2Platform</a>. 

@tutorial_1144_h2
Webアプリケーションで データベースを使用する

@tutorial_1145_p
# There are multiple ways to access a database from within web applications. Here are some examples if you use Tomcat or JBoss. 

@tutorial_1146_h3
エンベッドモード

@tutorial_1147_p
# The (currently) simplest solution is to use the database in the embedded mode, that means open a connection in your application when it starts (a good solution is using a Servlet Listener, see below), or when a session starts. A database can be accessed from multiple sessions and applications at the same time, as long as they run in the same process. Most Servlet Containers (for example Tomcat) are just using one process, so this is not a problem (unless you run Tomcat in clustered mode). Tomcat uses multiple threads and multiple classloaders. If multiple applications access the same database at the same time, you need to put the database jar in the <code>shared/lib</code> or <code>server/lib</code> directory. It is a good idea to open the database when the web application starts, and close it when the web application stops. If using multiple applications, only one (any) of them needs to do that. In the application, an idea is to use one connection per Session, or even one connection per request (action). Those connections should be closed after use if possible (but it's not that bad if they don't get closed). 

@tutorial_1148_h3
サーバーモード

@tutorial_1149_p
# The server mode is similar, but it allows you to run the server in another process. 

@tutorial_1150_h3
データベースの起動と終了にServletリスナーを使用する

@tutorial_1151_p
# Add the h2*.jar file to your web application, and add the following snippet to your web.xml file (between the <code>context-param</code> and the <code>filter</code> section): 

@tutorial_1152_p
# For details on how to access the database, see the file <code>DbStarter.java</code>. By default this tool opens an embedded connection using the database URL <code>jdbc:h2:~/test</code>, user name <code>sa</code>, and password <code>sa</code>. If you want to use this connection within your servlet, you can access as follows: 

@tutorial_1153_code
#DbStarter

@tutorial_1154_p
# can also start the TCP server, however this is disabled by default. To enable it, use the parameter <code>db.tcpServer</code> in the file <code>web.xml</code>. Here is the complete list of options. These options need to be placed between the <code>description</code> tag and the <code>listener</code> / <code>filter</code> tags: 

@tutorial_1155_p
# When the web application is stopped, the database connection will be closed automatically. If the TCP server is started within the <code>DbStarter</code>, it will also be stopped automatically. 

@tutorial_1156_h3
#Using the H2 Console Servlet

@tutorial_1157_p
# The H2 Console is a standalone application and includes its own web server, but it can be used as a servlet as well. To do that, include the the <code>h2*.jar</code> file in your application, and add the following configuration to your <code>web.xml</code>: 

@tutorial_1158_p
# For details, see also <code>src/tools/WEB-INF/web.xml</code>. 

@tutorial_1159_p
# To create a web application with just the H2 Console, run the following command: 

@tutorial_1160_h2
CSV (Comma Separated Values) サポート

@tutorial_1161_p
# The CSV file support can be used inside the database using the functions <code>CSVREAD</code> and <code>CSVWRITE</code>, or it can be used outside the database as a standalone tool. 

@tutorial_1162_h3
データベース内からCSVファイルに書き込む

@tutorial_1163_p
# The built-in function <code>CSVWRITE</code> can be used to create a CSV file from a query. Example: 

@tutorial_1164_h3
データベース内からCSVファイルを読み込む

@tutorial_1165_p
# A CSV file can be read using the function <code>CSVREAD</code>. Example: 

@tutorial_1166_h3
JavaアプリケーションからCSVファイルに書き込む

@tutorial_1167_p
# The <code>Csv</code> tool can be used in a Java application even when not using a database at all. Example: 

@tutorial_1168_h3
JavaアプリケーションからCSVファイルを読み込む

@tutorial_1169_p
# It is possible to read a CSV file without opening a database. Example: 

@tutorial_1170_h2
アップグレード、 バックアップ、修復

@tutorial_1171_h3
データベースのアップグレー

@tutorial_1172_p
# The recommended way to upgrade from one version of the database engine to the next version is to create a backup of the database (in the form of a SQL script) using the old engine, and then execute the SQL script using the new engine. 

@tutorial_1173_h3
バックアップ

@tutorial_1174_p
# There are different ways to backup a database. For example, it is possible to copy the database files. However, this is not recommended while the database is in use. Also, the database files are not human readable and quite large. The recommended way to backup a database is to create a compressed SQL script file. This can be done using the <code>Script</code> tool: 

@tutorial_1175_p
# It is also possible to use the SQL command <code>SCRIPT</code> to create the backup of the database. For more information about the options, see the SQL command <code>SCRIPT</code>. The backup can be done remotely, however the file will be created on the server side. The built in FTP server could be used to retrieve the file from the server. 

@tutorial_1176_h3
修復

@tutorial_1177_p
# To restore a database from a SQL script file, you can use the <code>RunScript</code> tool: 

@tutorial_1178_p
# For more information about the options, see the SQL command <code>RUNSCRIPT</code>. The restore can be done remotely, however the file needs to be on the server side. The built in FTP server could be used to copy the file to the server. It is also possible to use the SQL command <code>RUNSCRIPT</code> to execute a SQL script. SQL script files may contain references to other script files, in the form of <code>RUNSCRIPT</code> commands. However, when using the server mode, the references script files need to be available on the server side. 

@tutorial_1179_h3
オンラインバックアップ

@tutorial_1180_p
# The <code>BACKUP</code> SQL statement and the <code>Backup</code> tool both create a zip file with all database files. However, the contents of this file are not human readable. 

@tutorial_1181_p
# Unlike than the SCRIPT statement, the <code>BACKUP</code> statement does not lock the database objects when using the multi-threaded mode, and therefore does not block other users. The resulting backup is transactionally consistent: 

@tutorial_1182_p
# The <code>Backup</code> tool (<code>org.h2.tools.Backup</code>) can not be used to create a online backup; the database must not be in use while running this program. 

@tutorial_1183_p
# Creating a backup by copying the database files while the database is running is not supported, except if the file systems support creating snapshots. The problem is that it can't be guaranteed that the data is copied in the right order. 

@tutorial_1184_h2
#Command Line Tools

@tutorial_1185_p
# This database comes with a number of command line tools. To get more information about a tool, start it with the parameter '-?', for example: 

@tutorial_1186_p
# The command line tools are: 

@tutorial_1187_code
バックアップ

@tutorial_1188_li
# creates a backup of a database. 

@tutorial_1189_code
#ChangeFileEncryption

@tutorial_1190_li
# allows changing the file encryption password or algorithm of a database. 

@tutorial_1191_code
#Console

@tutorial_1192_li
# starts the browser based H2 Console. 

@tutorial_1193_code
#ConvertTraceFile

@tutorial_1194_li
# converts a .trace.db file to a Java application and SQL script. 

@tutorial_1195_code
#CreateCluster

@tutorial_1196_li
# creates a cluster from a standalone database. 

@tutorial_1197_code
#DeleteDbFiles

@tutorial_1198_li
# deletes all files belonging to a database. 

@tutorial_1199_code
#Recover

@tutorial_1200_li
# helps recovering a corrupted database. 

@tutorial_1201_code
#Restore

@tutorial_1202_li
# restores a backup of a database. 

@tutorial_1203_code
#RunScript

@tutorial_1204_li
# runs a SQL script against a database. 

@tutorial_1205_code
#Script

@tutorial_1206_li
# allows converting a database to a SQL script for backup or migration. 

@tutorial_1207_code
Server

@tutorial_1208_li
# is used in the server mode to start a H2 server. 

@tutorial_1209_code
#Shell

@tutorial_1210_li
# is a command line database tool. 

@tutorial_1211_p
# The tools can also be called from an application by calling the main or another public method. For details, see the Javadoc documentation. 

@tutorial_1212_h2
#The Shell Tool

@tutorial_1213_p
# The Shell tool is a simple interactive command line tool. To start it, type: 

@tutorial_1214_p
# You will be asked for a database URL, JDBC driver, user name, and password. The connection setting can also be set as command line parameters. After connecting, you will get the list of options. The built-in commands don't need to end with a semicolon, but SQL statements are only executed if the line ends with a semicolon <code>;</code>. This allows to enter multi-line statements: 

@tutorial_1215_p
# By default, results are printed as a table. For results with many column, consider using the list mode: 

@tutorial_1216_h2
OpenOffice Baseを使用する

@tutorial_1217_p
# OpenOffice.org Base supports database access over the JDBC API. To connect to a H2 database using OpenOffice Base, you first need to add the JDBC driver to OpenOffice. The steps to connect to a H2 database are: 

@tutorial_1218_li
#Start OpenOffice Writer, go to [Tools], [Options] 

@tutorial_1219_li
#Make sure you have selected a Java runtime environment in OpenOffice.org / Java 

@tutorial_1220_li
#Click [Class Path...], [Add Archive...] 

@tutorial_1221_li
#Select your h2 jar file (location is up to you, could be wherever you choose) 

@tutorial_1222_li
#Click [OK] (as much as needed), stop OpenOffice (including the Quickstarter) 

@tutorial_1223_li
#Start OpenOffice Base 

@tutorial_1224_li
#Connect to an existing database; select [JDBC]; [Next] 

@tutorial_1225_li
#Example datasource URL: <code>jdbc:h2:~/test</code> 

@tutorial_1226_li
#JDBC driver class: <code>org.h2.Driver</code> 

@tutorial_1227_p
# Now you can access the database stored in the current users home directory. 

@tutorial_1228_p
# To use H2 in NeoOffice (OpenOffice without X11): 

@tutorial_1229_li
#In NeoOffice, go to [NeoOffice], [Preferences] 

@tutorial_1230_li
#Look for the page under [NeoOffice], [Java] 

@tutorial_1231_li
#Click [Class Path], [Add Archive...] 

@tutorial_1232_li
#Select your h2 jar file (location is up to you, could be wherever you choose) 

@tutorial_1233_li
#Click [OK] (as much as needed), restart NeoOffice. 

@tutorial_1234_p
# Now, when creating a new database using the "Database Wizard" : 

@tutorial_1235_li
#Click [File], [New], [Database]. 

@tutorial_1236_li
#Select [Connect to existing database] and the select [JDBC]. Click next. 

@tutorial_1237_li
#Example datasource URL: <code>jdbc:h2:~/test</code> 

@tutorial_1238_li
#JDBC driver class: <code>org.h2.Driver</code> 

@tutorial_1239_p
# Another solution to use H2 in NeoOffice is: 

@tutorial_1240_li
#Package the h2 jar within an extension package 

@tutorial_1241_li
#Install it as a Java extension in NeoOffice 

@tutorial_1242_p
# This can be done by create it using the NetBeans OpenOffice plugin. See also <a href="http://wiki.services.openoffice.org/wiki/Extensions_development_java">Extensions Development</a>. 

@tutorial_1243_h2
Java Web Start / JNLP

@tutorial_1244_p
# When using Java Web Start / JNLP (Java Network Launch Protocol), permissions tags must be set in the .jnlp file, and the application .jar file must be signed. Otherwise, when trying to write to the file system, the following exception will occur: <code>java.security.AccessControlException</code>: access denied (<code>java.io.FilePermission ... read</code>). Example permission tags: 

@tutorial_1245_h2
#Using a Connection Pool

@tutorial_1246_p
# For H2, opening a connection is fast if the database is already open. Still, using a connection pool improves performance if you open and close connections a lot. A simple connection pool is included in H2. It is based on the <a href="http://www.source-code.biz/snippets/java/8.htm">Mini Connection Pool Manager</a> from Christian d'Heureuse. There are other, more complex, open source connection pools available, for example the <a href="http://jakarta.apache.org/commons/dbcp/">Apache Commons DBCP</a>. For H2, it is about twice as faster to get a connection from the built-in connection pool than to get one using <code>DriverManager.getConnection()</code>.The build-in connection pool is used as follows: 

@tutorial_1247_h2
フルテキストサーチ

@tutorial_1248_p
# H2 includes two fulltext search implementations. One is using Apache Lucene, and the other (the native implementation) stores the index data in special tables in the database. 

@tutorial_1249_h3
#Using the Native Fulltext Search

@tutorial_1250_p
# To initialize, call: 

@tutorial_1251_p
# You need to initialize it in each database where you want to use it. Afterwards, you can create a fulltext index for a table using: 

@tutorial_1252_p
# PUBLIC is the schema name, TEST is the table name. The list of column names (column separated) is optional, in this case all columns are indexed. The index is updated in realtime. To search the index, use the following query: 

@tutorial_1253_p
# This will produce a result set that contains the query needed to retrieve the data: 

@tutorial_1254_p
# To get the raw data, use <code>FT_SEARCH_DATA('Hello', 0, 0);</code>. The result contains the columns <code>SCHEMA</code> (the schema name), <code>TABLE</code> (the table name), <code>COLUMNS</code> (an array of column names), and <code>KEYS</code> (an array of objects). To join a table, use a join as in: <code>SELECT T.* FROM FT_SEARCH_DATA('Hello', 0, 0) FT, TEST T WHERE FT.TABLE='TEST' AND T.ID=FT.KEYS[0];</code> 

@tutorial_1255_p
# You can also call the index from within a Java application: 

@tutorial_1256_h3
Luceneフルテキストサーチを使用する

@tutorial_1257_p
# To use the Lucene full text search, you need the Lucene library in the classpath. How to do that depends on the application; if you use the H2 Console, you can add the Lucene jar file to the environment variables <code>H2DRIVERS</code> or <code>CLASSPATH</code>. To initialize the Lucene fulltext search in a database, call: 

@tutorial_1258_p
# You need to initialize it in each database where you want to use it. Afterwards, you can create a full text index for a table using: 

@tutorial_1259_p
# PUBLIC is the schema name, TEST is the table name. The list of column names (column separated) is optional, in this case all columns are indexed. The index is updated in realtime. To search the index, use the following query: 

@tutorial_1260_p
# This will produce a result set that contains the query needed to retrieve the data: 

@tutorial_1261_p
# To get the raw data, use <code>FTL_SEARCH_DATA('Hello', 0, 0);</code>. The result contains the columns <code>SCHEMA</code> (the schema name), <code>TABLE</code> (the table name), <code>COLUMNS</code> (an array of column names), and <code>KEYS</code> (an array of objects). To join a table, use a join as in: <code>SELECT T.* FROM FTL_SEARCH_DATA('Hello', 0, 0) FT, TEST T WHERE FT.TABLE='TEST' AND T.ID=FT.KEYS[0];</code> 

@tutorial_1262_p
# You can also call the index from within a Java application: 

@tutorial_1263_h2
#User-Defined Variables

@tutorial_1264_p
# This database supports user-defined variables. Variables start with <code>@</code> and can be used wherever expressions or parameters are allowed. Variables are not persisted and session scoped, that means only visible from within the session in which they are defined. A value is usually assigned using the SET command: 

@tutorial_1265_p
# The value can also be changed using the SET() method. This is useful in queries: 

@tutorial_1266_p
# Variables that are not set evaluate to <code>NULL</code>. The data type of a user-defined variable is the data type of the value assigned to it, that means it is not necessary (or possible) to declare variable names before using them. There are no restrictions on the assigned values; large objects (LOBs) are supported as well. 

@tutorial_1267_h2
#Date and Time

@tutorial_1268_p
# Date, time and timestamp values support ISO 8601 formatting, including time zone: 

@tutorial_1269_p
# If the time zone is not set, the value is parsed using the current time zone setting of the system. Date and time information is stored in H2 database files in GMT (Greenwich Mean Time). If the database is opened using another system time zone, the date and time will change accordingly. If you want to move a database from one time zone to the other and don't want this to happen, you need to create a SQL script file using the <code>SCRIPT</code> command or <code>Script</code> tool, and then load the database using the <code>RUNSCRIPT</code> command or the <code>RunScript</code> tool in the new time zone. 

@tutorial_1270_h2
#Using Spring

@tutorial_1271_p
# Use the following configuration to start and stop the H2 TCP server using the Spring Framework: 

@tutorial_1272_p
# The <code>destroy-method</code> will help prevent exceptions on hot-redeployment or when restarting the server.