New experimental system property "h2.modifyOnWrite".

h2/src/main/org/h2/store/LobStorage.java

@@ -95,11 +95,32 @@ public class LobStorage {
                 Statement stat = conn.createStatement();
                 // stat.execute("SET UNDO_LOG 0");
                 // stat.execute("SET REDO_LOG_BINARY 0");
-                stat.execute("CREATE TABLE IF NOT EXISTS " + LOBS +
+                boolean create = true;
+                PreparedStatement prep = conn.prepareStatement(
+                        "SELECT ZERO() FROM INFORMATION_SCHEMA.COLUMNS WHERE " +
+                        "TABLE_SCHEMA=? AND TABLE_NAME=? AND COLUMN_NAME=?");
+                prep.setString(1, "INFORMATION_SCHEMA");
+                prep.setString(2, "LOB_MAP");
+                prep.setString(3, "POS");
+                ResultSet rs;
+                rs = prep.executeQuery();
+                if (rs.next()) {
+                    prep = conn.prepareStatement(
+                            "SELECT ZERO() FROM INFORMATION_SCHEMA.TABLES WHERE " +
+                            "TABLE_SCHEMA=? AND TABLE_NAME=?");
+                    prep.setString(1, "INFORMATION_SCHEMA");
+                    prep.setString(2, "LOB_DATA");
+                    rs = prep.executeQuery();
+                    if (rs.next()) {
+                        create = false;
+                    }
+                }
+                if (create) {
+                    stat.execute("CREATE CACHED TABLE IF NOT EXISTS " + LOBS +
                             "(ID BIGINT PRIMARY KEY, BYTE_COUNT BIGINT, TABLE INT) HIDDEN");
                     stat.execute("CREATE INDEX IF NOT EXISTS " +
                             "INFORMATION_SCHEMA.INDEX_LOB_TABLE ON " + LOBS + "(TABLE)");
-                stat.execute("CREATE TABLE IF NOT EXISTS " + LOB_MAP +
+                    stat.execute("CREATE CACHED TABLE IF NOT EXISTS " + LOB_MAP +
                             "(LOB BIGINT, SEQ INT, POS BIGINT, HASH INT, BLOCK BIGINT, PRIMARY KEY(LOB, SEQ)) HIDDEN");
                     // TODO the column name OFFSET was used in version 1.3.156,
                     // so this can be remove in a later version
@@ -108,9 +129,9 @@ public class LobStorage {
                     stat.execute("ALTER TABLE " + LOB_MAP + " DROP COLUMN IF EXISTS \"OFFSET\"");
                     stat.execute("CREATE INDEX IF NOT EXISTS " +
                             "INFORMATION_SCHEMA.INDEX_LOB_MAP_DATA_LOB ON " + LOB_MAP + "(BLOCK, LOB)");
-                stat.execute("CREATE TABLE IF NOT EXISTS " + LOB_DATA +
+                    stat.execute("CREATE CACHED TABLE IF NOT EXISTS " + LOB_DATA +
                             "(BLOCK BIGINT PRIMARY KEY, COMPRESSED INT, DATA BINARY) HIDDEN");
-                ResultSet rs;
+                }
                 rs = stat.executeQuery("SELECT MAX(BLOCK) FROM " + LOB_DATA);
                 rs.next();
                 nextBlock = rs.getLong(1) + 1;

h2/src/main/org/h2/table/MetaTable.java

@@ -601,6 +601,10 @@ public class MetaTable extends Table {
         return s == null ? "" : s;
     }
 
+    private boolean hideTable(Table table, Session session) {
+        return table.isHidden() && session != database.getSystemSession();
+    }
+
     /**
      * Generate the data for the given metadata table using the given first and
      * last row filters.
@@ -632,7 +636,7 @@ public class MetaTable extends Table {
                 if (!checkIndex(session, tableName, indexFrom, indexTo)) {
                     continue;
                 }
-                if (table.isHidden()) {
+                if (hideTable(table, session)) {
                     continue;
                 }
                 String storageType;
@@ -678,7 +682,7 @@ public class MetaTable extends Table {
                 if (!checkIndex(session, tableName, indexFrom, indexTo)) {
                     continue;
                 }
-                if (table.isHidden()) {
+                if (hideTable(table, session)) {
                     continue;
                 }
                 Column[] cols = table.getColumns();
@@ -744,7 +748,7 @@ public class MetaTable extends Table {
                 if (!checkIndex(session, tableName, indexFrom, indexTo)) {
                     continue;
                 }
-                if (table.isHidden()) {
+                if (hideTable(table, session)) {
                     continue;
                 }
                 ArrayList<Index> indexes = table.getIndexes();
@@ -1209,7 +1213,7 @@ public class MetaTable extends Table {
         case TABLE_PRIVILEGES: {
             for (Right r : database.getAllRights()) {
                 Table table = r.getGrantedTable();
-                if (table == null || table.isHidden()) {
+                if (table == null || hideTable(table, session)) {
                     continue;
                 }
                 String tableName = identifier(table.getName());
@@ -1223,7 +1227,7 @@ public class MetaTable extends Table {
         case COLUMN_PRIVILEGES: {
             for (Right r : database.getAllRights()) {
                 Table table = r.getGrantedTable();
-                if (table == null || table.isHidden()) {
+                if (table == null || hideTable(table, session)) {
                     continue;
                 }
                 String tableName = identifier(table.getName());
@@ -1355,7 +1359,7 @@ public class MetaTable extends Table {
                 String checkExpression = null;
                 IndexColumn[] indexColumns = null;
                 Table table = constraint.getTable();
-                if (table.isHidden()) {
+                if (hideTable(table, session)) {
                     continue;
                 }
                 Index index = constraint.getUniqueIndex();