Skip to content

H
h2database
切换分支/标签
查找文件
Normal viewHistoryPermalink
faq.html 4.5 KB
Newer Older
Thomas Mueller's avatar
--no commit message
23c4f01c
 
Thomas Mueller committed
1 2 3 4 5 
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<!--
Copyright 2004-2006 H2 Group. Licensed under the H2 License, Version 1.0 (http://h2database.com/html/license.html).
Initial Developer: H2 Group
-->
Thomas Mueller's avatar
--no commit message
b492f851
 
Thomas Mueller committed
6 
<html><head><meta http-equiv="Content-Type" content="text/html;charset=utf-8" /><title>
Thomas Mueller's avatar
--no commit message
23c4f01c
 
Thomas Mueller committed
7 
Frequently Asked Questions
Thomas Mueller's avatar
--no commit message
b492f851
 
Thomas Mueller committed
8 
</title><link rel="stylesheet" type="text/css" href="stylesheet.css" />
Thomas Mueller's avatar
--no commit message
23c4f01c
 
Thomas Mueller committed
9 10 11 12 13 14 15 16 17 
<script type="text/javascript" src="navigation.js"></script>
</head><body onload="frameMe();">
<table class="content"><tr class="content"><td class="content"><div class="contentDiv">

<h1>Frequently Asked Questions</h1>

<h3>Are there any known bugs? When is the next release?</h3>
Usually, bugs get fixes as they are found. There is a release every few weeks.
Here is the list of known and confirmed issues as of
Thomas Mueller's avatar
--no commit message
d536591a
 
Thomas Mueller committed
18 
2007-03-20:
Thomas Mueller's avatar
--no commit message
23c4f01c
 
Thomas Mueller committed
19 
<ul>
Thomas Mueller's avatar
--no commit message
a0f72ec6
 
Thomas Mueller committed
20 
<li>Can not build using the test cases ant with JDK 1.3 at the moment. However most things are fixed.
Thomas Mueller's avatar
--no commit message
b492f851
 
Thomas Mueller committed
21 
</li><li>Some problems have been found with right outer join. Internally, it is converted to left outer join, which
Thomas Mueller's avatar
--no commit message
23c4f01c
 
Thomas Mueller committed
22 
    does not always produce the correct results when used in combination with other joins.
Thomas Mueller's avatar
--no commit message
b492f851
 
Thomas Mueller committed
23 
</li></ul>
Thomas Mueller's avatar
--no commit message
23c4f01c
 
Thomas Mueller committed
24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 

<h3>Is this Database Engine Open Source?</h3>
Yes. It is free to use and distribute, and the source code is included.
See also under license.

<h3>Is the GCJ version stable? Faster?</h3>
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.

<h3>Is it Reliable?</h3>
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 as this is a relatively new product, there are probably
some problems that have not yet been found.
Areas that are not completely tested:
<ul>
<li>Platforms other than Windows XP and the Sun JVM 1.4
Thomas Mueller's avatar
--no commit message
b492f851
 
Thomas Mueller committed
44 45 46 47 48 49 50 51 52 53 54 55 
</li><li>Data types BLOB, CLOB, VARCHAR_IGNORECASE, OTHER
</li><li>Cluster mode, 2-Phase Commit, Savepoints
</li><li>Server mode (well tested, but not as well as Embedded mode)
</li><li>Multi-Threading and using multiple connections
</li><li>Updatable result sets
</li><li>Referential integrity and check constraints, Triggers
</li><li>ALTER TABLE statements, Views, Linked Tables, Schema, UNION
</li><li>Not all built-in functions are completely tested
</li><li>The Optimizer may not always select the best plan
</li><li>24/7 operation and large databases (500 MB and up)
</li><li>Wide indexes with large VARCHAR or VARBINARY columns and / or with a lot of columns
</li></ul>
Thomas Mueller's avatar
--no commit message
23c4f01c
 
Thomas Mueller committed
56 57 58 59 

Areas considered Experimental:
<ul>
<li>ODBC driver and the GCJ native version on Windows
Thomas Mueller's avatar
--no commit message
b492f851
 
Thomas Mueller committed
60 61 
</li><li>Linear Hash Index
</li><li>Compatibility modes for other databases (only some features are implemented)
Thomas Mueller's avatar
--no commit message
d536591a
 
Thomas Mueller committed
62 
</li><li>The ARRAY data type and related functionality.
Thomas Mueller's avatar
--no commit message
b492f851
 
Thomas Mueller committed
63 
</li></ul>
Thomas Mueller's avatar
--no commit message
23c4f01c
 
Thomas Mueller committed
64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 

<h3>How to Create a New Database?</h3>
By default, a new database is automatically created if it does not yet exist.

<h3>How to Connect to a Database?</h3>
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:
<pre>
Class.forName("org.h2.Driver");
Connection conn = DriverManager.getConnection("jdbc:h2:test", "sa", "");
</pre>

<h3>Where are the Database Files Stored?</h3>
If the base directory is not set, 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 [Installation Directory]/bin.
The base directory can be set in the database URL. A fixed or relative path can be used. When using the URL
jdbc:h2:file:data/sample, the database is stored in the directory data (relative to the current working directory).
The directory must exist. It is also possible to use the fully qualified directory (and for Windows, drive) name.
Example: jdbc:h2:file:C:/data/test

<h3>What is the Size Limit of a Database?</h3>
The theoretical limit is currently 256 GB for the data. This number is excluding BLOB and CLOB data:
Every CLOB or BLOB can be up to 256 GB as well. The size limit of the index data is 256 GB as well.

</div></td></tr></table></body></html>