When enabling autocommit, the transaction is now committed (as required by the JDBC API).

h2/src/docsrc/html/changelog.html

@@ -18,7 +18,8 @@ Change Log
 <h1>Change Log</h1>
 
 <h2>Next Version (unreleased)</h2>
-<ul><li>The shell script <code>h2.sh</code> did not work with spaces in the path.
+<ul><li>When enabling autocommit, the transaction is now committed (as required by the JDBC API).
+</li><li>The shell script <code>h2.sh</code> did not work with spaces in the path.
     It also works now with quoted spaces in the argument list.
     Thanks a lot to Shimizu Fumiyuki for the patch!
 </li><li>If the transaction log could not be truncated because of an uncommitted transaction,

h2/src/main/org/h2/engine/Session.java

@@ -349,7 +349,10 @@ public class Session extends SessionWithState {
     }
 
     public void setAutoCommit(boolean b) {
-        autoCommit = b;
+        if (autoCommit != b) {
+            commit(false);
+            autoCommit = b;
+        }
     }
 
     public int getLockTimeout() {

h2/src/test/org/h2/test/db/TestTransaction.java

@@ -36,6 +36,7 @@ public class TestTransaction extends TestBase {
     }
 
     public void test() throws SQLException {
+        testCommitOnAutoCommitChange();
         testConcurrentSelectForUpdate();
         testLogMode();
         testRollback();
@@ -48,6 +49,36 @@ public class TestTransaction extends TestBase {
         deleteDb("transaction");
     }
 
+    private void testCommitOnAutoCommitChange() throws SQLException {
+        deleteDb("transaction");
+        Connection conn = getConnection("transaction");
+        Statement stat = conn.createStatement();
+        stat.execute("create table test(id int primary key)");
+
+        Connection conn2 = getConnection("transaction");
+        Statement stat2 = conn2.createStatement();
+
+        conn.setAutoCommit(false);
+        stat.execute("insert into test values(1)");
+
+        // should have no effect
+        conn.setAutoCommit(false);
+
+        assertThrows(ErrorCode.LOCK_TIMEOUT_1, stat2).
+            executeQuery("select count(*) from test");
+
+        // should commit
+        conn.setAutoCommit(true);
+
+        ResultSet rs = stat2.executeQuery("select * from test");
+        assertTrue(rs.next());
+
+        stat.execute("drop table test");
+
+        conn2.close();
+        conn.close();
+    }
+
     private void testLogMode() throws SQLException {
         if (config.memory) {
             return;