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Posted to derby-commits@db.apache.org by oy...@apache.org on 2007/10/15 15:56:23 UTC
svn commit: r584791 - in /db/derby/code/branches/10.3/java:
engine/org/apache/derby/impl/jdbc/
engine/org/apache/derby/impl/store/raw/data/
testing/org/apache/derbyTesting/functionTests/tests/jdbc4/
testing/org/apache/derbyTesting/functionTests/tests/j...
Author: oysteing
Date: Mon Oct 15 06:56:18 2007
New Revision: 584791
URL: http://svn.apache.org/viewvc?rev=584791&view=rev
Log:
DERBY-3098: If allowed by transaction isolation level, release locks when [BC]lob.free() is called.
This changes the following files:
M java/engine/org/apache/derby/impl/jdbc/EmbedClob.java
Only initialize storeStream once.
M java/engine/org/apache/derby/impl/store/raw/data/OverflowInputStream.java
Do not lock for entire duration anymore, but until corresponding
BaseContainerHandle has been closed. Also, make sure that locking
only happens once.
M java/testing/org/apache/derbyTesting/functionTests/tests/jdbc4/BlobTest.java
Add tests to test locking of Blob after free() for different isolation
levels. Also, moved code from setUp that is only relevant to one test
case to that specific test case.
M java/testing/org/apache/derbyTesting/functionTests/tests/jdbc4/ClobTest.java
Add tests to test locking of Blob after free() for different isolation
levels. Also, moved code from setUp that is only relevant to one test
case to that specific test case.
M java/testing/org/apache/derbyTesting/functionTests/tests/jdbcapi/BlobClob4BlobTest.java
Test that locks on Blob/Clob are released when transaction commits.
Modified:
db/derby/code/branches/10.3/java/engine/org/apache/derby/impl/jdbc/EmbedClob.java
db/derby/code/branches/10.3/java/engine/org/apache/derby/impl/store/raw/data/OverflowInputStream.java
db/derby/code/branches/10.3/java/testing/org/apache/derbyTesting/functionTests/tests/jdbc4/BlobTest.java
db/derby/code/branches/10.3/java/testing/org/apache/derbyTesting/functionTests/tests/jdbc4/ClobTest.java
db/derby/code/branches/10.3/java/testing/org/apache/derbyTesting/functionTests/tests/jdbcapi/BlobClob4BlobTest.java
Modified: db/derby/code/branches/10.3/java/engine/org/apache/derby/impl/jdbc/EmbedClob.java
URL: http://svn.apache.org/viewvc/db/derby/code/branches/10.3/java/engine/org/apache/derby/impl/jdbc/EmbedClob.java?rev=584791&r1=584790&r2=584791&view=diff
==============================================================================
--- db/derby/code/branches/10.3/java/engine/org/apache/derby/impl/jdbc/EmbedClob.java (original)
+++ db/derby/code/branches/10.3/java/engine/org/apache/derby/impl/jdbc/EmbedClob.java Mon Oct 15 06:56:18 2007
@@ -144,7 +144,7 @@
SanityManager.ASSERT(storeStream instanceof Resetable);
try {
- ((Resetable) storeStream).initStream();
+ this.clob = new StoreStreamClob(storeStream, this);
} catch (StandardException se) {
if (se.getMessageId().equals(SQLState.DATA_CONTAINER_CLOSED)) {
throw StandardException
@@ -152,7 +152,6 @@
}
throw se;
}
- this.clob = new StoreStreamClob(storeStream, this);
}
con.addLOBMapping (this);
}
Modified: db/derby/code/branches/10.3/java/engine/org/apache/derby/impl/store/raw/data/OverflowInputStream.java
URL: http://svn.apache.org/viewvc/db/derby/code/branches/10.3/java/engine/org/apache/derby/impl/store/raw/data/OverflowInputStream.java?rev=584791&r1=584790&r2=584791&view=diff
==============================================================================
--- db/derby/code/branches/10.3/java/engine/org/apache/derby/impl/store/raw/data/OverflowInputStream.java (original)
+++ db/derby/code/branches/10.3/java/engine/org/apache/derby/impl/store/raw/data/OverflowInputStream.java Mon Oct 15 06:56:18 2007
@@ -30,7 +30,6 @@
import org.apache.derby.iapi.store.raw.LockingPolicy;
import org.apache.derby.iapi.store.access.TransactionController;
-import java.io.InputStream;
import java.io.IOException;
/**
@@ -49,6 +48,9 @@
protected int firstOverflowId;
// the row to lock for Blobs/Clobs
protected RecordHandle recordToLock;
+
+ // Make sure record is only locked once.
+ private boolean initialized = false;
public OverflowInputStream(ByteHolder bh, BaseContainerHandle owner,
long overflowPage, int overflowId, RecordHandle recordToLock)
@@ -133,41 +135,37 @@
fillByteHolder();
}
- /*
- Initialize. Reopen the container. This will have the effect of
- getting an intent shared lock on the table, which will stay around until
- the end of the transaction (or until the enclosing blob/clob object is
- closed). Also get a read lock on the appropriate row.
- */
+ /**
+ * Initialize. Reopen the container. This will have the effect of
+ * getting an intent shared lock on the table, which will stay around until
+ * the enclosing blob/clob object is closed, or until the end of the
+ * transaction. Also get a read lock on the appropriate row.
+ *
+ * @throws org.apache.derby.iapi.error.StandardException
+ */
public void initStream() throws StandardException
{
- // it is possible that the transaction in which the stream was
+ if (initialized) return;
+
+ // it is possible that the transaction in which the stream was
// created is committed and no longer valid
// dont want to get NPE but instead throw error that
// container was not opened
if (owner.getTransaction() == null)
throw StandardException.newException(SQLState.DATA_CONTAINER_CLOSED);
+
/*
- We might want to use the mode and isolation level of the container.
- This would have the advantage that, if the isolation level
- is READ_COMMITTED, resources would be freed if blobs/clob finalizers are
- called (e.g. they are garbage collected) before the end of transaction.
- If the mode was MODE_CONTAINER, openContainer would get an S lock on the
- table instead of an IS lock, and lockRecordForRead would have no effect.
-
- To do this, need to consider:
- Sometimes the container's locking policy may NOT reflect the correct
- locking policy. For example, if the container is a table (not an index)
- and Access handles the locking of the table via an index, the container's
- locking policy would be set to do no locking.
- Moreover, if the container is an index, the locking policy would
- always be set to do no locking.
+ We use isolation level READ_COMMITTED and reopen the container to
+ get a new container handle to use for locking. This way, the lock will
+ be freed when we the container handle is closed. This will happen in
+ closeStream() or when the transaction commits.
+ Hence, locks will be released before the end of transaction if
+ blobs/clobs are explicitly released.
*/
-
LockingPolicy lp =
owner.getTransaction().newLockingPolicy(
LockingPolicy.MODE_RECORD,
- TransactionController.ISOLATION_REPEATABLE_READ, true);
+ TransactionController.ISOLATION_READ_COMMITTED, true);
// reopen the container
owner = (BaseContainerHandle) owner.getTransaction().openContainer(
@@ -178,17 +176,19 @@
// thrown
owner.getLockingPolicy().lockRecordForRead(
owner.getTransaction(), owner, recordToLock, true, false);
+
+ initialized = true;
}
/*
- Close the container associated with this stream. (In the future if we use
- a read committed isolation mode, this will also free the associated IS
- table lock and the associated S row lock.)
+ Close the container associated with this stream. (This will also free the
+ associated IS table lock and the associated S row lock.)
*/
public void closeStream()
{
owner.close();
+ initialized = false;
}
}
Modified: db/derby/code/branches/10.3/java/testing/org/apache/derbyTesting/functionTests/tests/jdbc4/BlobTest.java
URL: http://svn.apache.org/viewvc/db/derby/code/branches/10.3/java/testing/org/apache/derbyTesting/functionTests/tests/jdbc4/BlobTest.java?rev=584791&r1=584790&r2=584791&view=diff
==============================================================================
--- db/derby/code/branches/10.3/java/testing/org/apache/derbyTesting/functionTests/tests/jdbc4/BlobTest.java (original)
+++ db/derby/code/branches/10.3/java/testing/org/apache/derbyTesting/functionTests/tests/jdbc4/BlobTest.java Mon Oct 15 06:56:18 2007
@@ -23,7 +23,9 @@
import junit.framework.*;
+import org.apache.derbyTesting.functionTests.util.streams.LoopingAlphabetStream;
import org.apache.derbyTesting.junit.BaseJDBCTestCase;
+import org.apache.derbyTesting.junit.DatabasePropertyTestSetup;
import org.apache.derbyTesting.junit.TestConfiguration;
import java.sql.*;
@@ -159,19 +161,13 @@
// Life span of Blob objects are limited by the transaction. Need
// autocommit off so Blob objects survive closing of result set.
getConnection().setAutoCommit(false);
-
- blob = BlobClobTestSetup.getSampleBlob(getConnection());
-
- //call the buildHashSetMethod to initialize the
- //HashSet with the method signatures that are exempted
- //from throwing a SQLException after free has been called
- //on the Clob object.
- buildHashSet();
}
protected void tearDown() throws Exception {
- blob.free();
- blob = null;
+ if (blob != null) {
+ blob.free();
+ blob = null;
+ }
excludedMethodSet = null;
super.tearDown();
}
@@ -204,6 +200,15 @@
*/
public void testFreeandMethodsAfterCallingFree()
throws SQLException {
+
+ blob = BlobClobTestSetup.getSampleBlob(getConnection());
+
+ //call the buildHashSetMethod to initialize the
+ //HashSet with the method signatures that are exempted
+ //from throwing a SQLException after free has been called
+ //on the Clob object.
+ buildHashSet();
+
blob.free();
//testing the idempotence of the free() method
//the method can be called multiple times on
@@ -603,16 +608,151 @@
//match
assertEquals(is_BeforeWrite, is_AfterWrite);
}
+
+ /**
+ * Test that a lock held on the corresponding row is released when free() is
+ * called on the Blob object.
+ * @throws java.sql.SQLException
+ */
+ public void testLockingAfterFree() throws SQLException
+ {
+ int id = initializeLongBlob(); // Opens blob object
+ executeParallelUpdate(id, true); // Test that timeout occurs
+
+ // Test that update goes through after the blob is closed
+ blob.free();
+ executeParallelUpdate(id, false);
+
+ commit();
+ }
+
+ /**
+ * Test that a lock held on the corresponding row is NOT released when
+ * free() is called on the Blob object if the isolation level is
+ * Repeatable Read
+ * @throws java.sql.SQLException
+ */
+ public void testLockingAfterFreeWithRR() throws SQLException
+ {
+ getConnection().
+ setTransactionIsolation(Connection.TRANSACTION_REPEATABLE_READ);
+ int id = initializeLongBlob(); // Opens blob object
+ executeParallelUpdate(id, true); // Test that timeout occurs
+
+ // Test that update still times out after the blob is closed
+ blob.free();
+ executeParallelUpdate(id, true);
+
+ // Test that the update goes through after the transaction has committed
+ commit();
+ executeParallelUpdate(id, false);
+ }
+
+ /**
+ * Test that a lock held on the corresponding row is released when
+ * free() is called on the Blob object if the isolation level is
+ * Read Uncommitted
+ * @throws java.sql.SQLException
+ */
+ public void testLockingAfterFreeWithDirtyReads() throws SQLException
+ {
+ getConnection().
+ setTransactionIsolation(Connection.TRANSACTION_READ_UNCOMMITTED);
+ int id = initializeLongBlob(); // Opens blob object
+ executeParallelUpdate(id, true); // Test that timeout occurs
+
+ // Test that update goes through after the blob is closed
+ blob.free();
+ executeParallelUpdate(id, false);
+
+ commit();
+ }
+
+
+ /**
+ * Insert a row with a large blob into the test table. Read the row from
+ * the database and assign the blob value to <code>blob</code>.
+ * @return The id of the row that was inserted
+ * @throws java.sql.SQLException
+ */
+ private int initializeLongBlob() throws SQLException
+ {
+ // Blob needs to be larger than one page for locking to occur
+ final int lobLength = 40000;
+
+ // Insert a long Blob
+ PreparedStatement ps =
+ prepareStatement("insert into BLOBCLOB(ID, BLOBDATA) values(?,?)");
+ int id =BlobClobTestSetup.getID();
+ ps.setInt(1, id);
+ ps.setBinaryStream(2,
+ new LoopingAlphabetStream(lobLength), lobLength);
+ ps.execute();
+ ps.close();
+ commit();
+
+ // Fetch the Blob object from the database
+ Statement st = createStatement();
+ ResultSet rs =
+ st.executeQuery("select BLOBDATA from BLOBCLOB where ID=" + id);
+ rs.next();
+ blob = rs.getBlob(1);
+ rs.close();
+ st.close();
+
+ return id;
+ }
+
+
+ /**
+ * Try to update the row with the given error. Flag a failure if a
+ * timeout occurs when not expected, and vice versa.
+ * @param id The id of the row to be updated
+ * @param timeoutExpected true if it is expected that the update times out
+ * @throws java.sql.SQLException
+ */
+ private void executeParallelUpdate(int id, boolean timeoutExpected)
+ throws SQLException
+ {
+ Connection conn2 = openDefaultConnection();
+ Statement stmt2 = conn2.createStatement();
+
+ try {
+ stmt2.executeUpdate("update BLOBCLOB set CLOBDATA = 'New' where id="
+ + id);
+ stmt2.close();
+ conn2.commit();
+ conn2.close();
+ if (timeoutExpected) {
+ fail("FAIL - should have gotten lock timeout");
+ }
+ } catch (SQLException se) {
+ stmt2.close();
+ conn2.rollback();
+ conn2.close();
+ if (timeoutExpected) {
+ assertSQLState(LOCK_TIMEOUT, se);
+ } else {
+ throw se;
+ }
+ }
+ }
+
+
/**
* Create test suite for this test.
*/
- public static Test suite() {
- return new BlobClobTestSetup(
- TestConfiguration.defaultSuite(
- BlobTest.class,
- false));
+ public static Test suite()
+ {
+ return new BlobClobTestSetup(
+ // Reduce lock timeouts so lock test case does not take too long
+ DatabasePropertyTestSetup.setLockTimeouts(
+ TestConfiguration.defaultSuite(BlobTest.class, false),
+ 2,
+ 4));
}
+ private static final String LOCK_TIMEOUT = "40XL1";
} // End class BlobTest
Modified: db/derby/code/branches/10.3/java/testing/org/apache/derbyTesting/functionTests/tests/jdbc4/ClobTest.java
URL: http://svn.apache.org/viewvc/db/derby/code/branches/10.3/java/testing/org/apache/derbyTesting/functionTests/tests/jdbc4/ClobTest.java?rev=584791&r1=584790&r2=584791&view=diff
==============================================================================
--- db/derby/code/branches/10.3/java/testing/org/apache/derbyTesting/functionTests/tests/jdbc4/ClobTest.java (original)
+++ db/derby/code/branches/10.3/java/testing/org/apache/derbyTesting/functionTests/tests/jdbc4/ClobTest.java Mon Oct 15 06:56:18 2007
@@ -44,6 +44,8 @@
* d) Whether the method is exempted in the NetworkClient
*
*/
+import org.apache.derbyTesting.functionTests.util.streams.LoopingAlphabetReader;
+import org.apache.derbyTesting.junit.DatabasePropertyTestSetup;
class ExemptClobMD {
// The Name of the method
private String methodName_;
@@ -154,19 +156,13 @@
// Life span of Clob objects are limited by the transaction. Need
// autocommit off so Clob objects survive closing of result set.
getConnection().setAutoCommit(false);
-
- clob = BlobClobTestSetup.getSampleClob(getConnection());
-
- //call the buildHashSetMethod to initialize the
- //HashSet with the method signatures that are exempted
- //from throwing a SQLException after free has been called
- //on the Clob object.
- buildHashSet();
}
protected void tearDown() throws Exception {
- clob.free();
- clob = null;
+ if (clob != null) {
+ clob.free();
+ clob = null;
+ }
excludedMethodSet = null;
super.tearDown();
}
@@ -198,21 +194,30 @@
*
*/
public void testFreeandMethodsAfterCallingFree()
- throws IllegalAccessException, InvocationTargetException, SQLException {
- InputStream asciiStream = clob.getAsciiStream();
- Reader charStream = clob.getCharacterStream();
- clob.free();
- //testing the idempotence of the free() method
- //the method can be called multiple times on
- //the same instance. subsequent calls after
- //the first are treated as no-ops
- clob.free();
-
- //clob becomes invalid after the first call
- //to the free method so testing calling
- //a method on this invalid object should throw
- //an SQLException
- buildMethodList(clob);
+ throws IllegalAccessException, InvocationTargetException, SQLException
+ {
+ clob = BlobClobTestSetup.getSampleClob(getConnection());
+
+ //call the buildHashSetMethod to initialize the
+ //HashSet with the method signatures that are exempted
+ //from throwing a SQLException after free has been called
+ //on the Clob object.
+ buildHashSet();
+
+ InputStream asciiStream = clob.getAsciiStream();
+ Reader charStream = clob.getCharacterStream();
+ clob.free();
+ //testing the idempotence of the free() method
+ //the method can be called multiple times on
+
+ //the first are treated as no-ops
+ clob.free();
+
+
+ //to the free method so testing calling
+ //a method on this invalid object should throw
+ //an SQLException
+ buildMethodList(clob);
}
/*
@@ -457,7 +462,7 @@
* c) length < 0
* d) pos + length > (length of LOB).
*
- * @throws SQLException.
+ * @throws SQLException
*/
public void testGetCharacterStreamLongExceptionConditions()
throws SQLException {
@@ -701,13 +706,148 @@
/**
- * Create test suite for this test.
+ * Test that a lock held on the corresponding row is released when free() is
+ * called on the Clob object.
+ * @throws java.sql.SQLException
+ */
+ public void testLockingAfterFree() throws SQLException
+ {
+ int id = initializeLongClob(); // Opens clob object
+ executeParallelUpdate(id, true); // Test that timeout occurs
+
+ // Test that update goes through after the clob is closed
+ clob.free();
+ executeParallelUpdate(id, false);
+
+ commit();
+ }
+
+
+ /**
+ * Test that a lock held on the corresponding row is NOT released when
+ * free() is called on the Clob object if the isolation level is
+ * Repeatable Read
+ * @throws java.sql.SQLException
+ */
+ public void testLockingAfterFreeWithRR() throws SQLException
+ {
+ getConnection().
+ setTransactionIsolation(Connection.TRANSACTION_REPEATABLE_READ);
+ int id = initializeLongClob(); // Opens clob object
+ executeParallelUpdate(id, true); // Test that timeout occurs
+
+ // Test that update still times out after the clob is closed
+ clob.free();
+ executeParallelUpdate(id, true);
+
+ // Test that the update goes through after the transaction has committed
+ commit();
+ executeParallelUpdate(id, false);
+ }
+
+
+ /**
+ * Test that a lock held on the corresponding row is released when
+ * free() is called on the Clob object if the isolation level is
+ * Read Uncommitted
+ * @throws java.sql.SQLException
+ */
+ public void testLockingAfterFreeWithDirtyReads() throws SQLException
+ {
+ getConnection().
+ setTransactionIsolation(Connection.TRANSACTION_READ_UNCOMMITTED);
+ int id = initializeLongClob(); // Opens clob object
+ executeParallelUpdate(id, true); // Test that timeout occurs
+
+ // Test that update goes through after the clob is closed
+ clob.free();
+ executeParallelUpdate(id, false);
+
+ commit();
+ }
+
+
+ /**
+ * Insert a row with a large clob into the test table. Read the row from
+ * the database and assign the clob value to <code>clob</code>.
+ * @return The id of the row that was inserted
+ * @throws java.sql.SQLException
*/
- public static Test suite() {
- return new BlobClobTestSetup(
- TestConfiguration.defaultSuite(
- ClobTest.class,
- false));
+ private int initializeLongClob() throws SQLException
+ {
+ // Clob needs to be larger than one page for locking to occur
+ final int lobLength = 40000;
+
+ // Insert a long Clob
+ PreparedStatement ps = prepareStatement(
+ "insert into BLOBCLOB(ID, CLOBDATA) values(?,?)");
+ int id = BlobClobTestSetup.getID();
+ ps.setInt(1,id);
+ ps.setCharacterStream(2, new LoopingAlphabetReader(lobLength), lobLength);
+ ps.execute();
+ ps.close();
+ commit();
+
+ // Fetch the Clob object from the database
+ Statement st = createStatement();
+ ResultSet rs =
+ st.executeQuery("select CLOBDATA from BLOBCLOB where ID=" + id);
+ rs.next();
+ clob = rs.getClob(1);
+ rs.close();
+ st.close();
+
+ return id;
+ }
+
+
+ /**
+ * Try to update the row with the given error. Flag a failure if a
+ * timeout occurs when not expected, and vice versa.
+ * @param id The id of the row to be updated
+ * @param timeoutExpected true if it is expected that the update times out
+ * @throws java.sql.SQLException
+ */
+ private void executeParallelUpdate(int id, boolean timeoutExpected)
+ throws SQLException
+ {
+ Connection conn2 = openDefaultConnection();
+ Statement stmt2 = conn2.createStatement();
+
+ try {
+ stmt2.executeUpdate("update BLOBCLOB set BLOBDATA = " +
+ "cast(X'FFFFFF' as blob) where ID=" + id);
+ stmt2.close();
+ conn2.commit();
+ conn2.close();
+ if (timeoutExpected) {
+ fail("FAIL - should have gotten lock timeout");
+ }
+ } catch (SQLException se) {
+ stmt2.close();
+ conn2.rollback();
+ conn2.close();
+ if (timeoutExpected) {
+ assertSQLState(LOCK_TIMEOUT, se);
+ } else {
+ throw se;
+ }
+ }
}
+
+ /**
+ * Create test suite for this test.
+ */
+ public static Test suite()
+ {
+ return new BlobClobTestSetup(
+ // Reduce lock timeouts so lock test case does not take too long
+ DatabasePropertyTestSetup.setLockTimeouts(
+ TestConfiguration.defaultSuite(ClobTest.class, false),
+ 2,
+ 4));
+ }
+
+ private static final String LOCK_TIMEOUT = "40XL1";
} // End class ClobTest
Modified: db/derby/code/branches/10.3/java/testing/org/apache/derbyTesting/functionTests/tests/jdbcapi/BlobClob4BlobTest.java
URL: http://svn.apache.org/viewvc/db/derby/code/branches/10.3/java/testing/org/apache/derbyTesting/functionTests/tests/jdbcapi/BlobClob4BlobTest.java?rev=584791&r1=584790&r2=584791&view=diff
==============================================================================
--- db/derby/code/branches/10.3/java/testing/org/apache/derbyTesting/functionTests/tests/jdbcapi/BlobClob4BlobTest.java (original)
+++ db/derby/code/branches/10.3/java/testing/org/apache/derbyTesting/functionTests/tests/jdbcapi/BlobClob4BlobTest.java Mon Oct 15 06:56:18 2007
@@ -1255,6 +1255,11 @@
checkException(LOCK_TIMEOUT, se);
}
assertEquals("FAIL: clob length changed", 10000, clob.length());
+
+ // Test that update goes through after the transaction is committed
+ commit();
+ stmt2.executeUpdate("update testClob set b = b + 1 where b = 10000");
+
stmt2.close();
conn2.rollback();
conn2.close();
@@ -1307,12 +1312,17 @@
stmt2.executeUpdate(
"update testClob set el = 'smurfball' where b = 1");
stmt2.close(); // Cleanup on fail
- conn2.commit();
+ conn2.rollback();
conn2.close();
fail("FAIL - statement should timeout");
} catch (SQLException se) {
checkException(LOCK_TIMEOUT, se);
}
+
+ // Test that update goes through after the transaction is committed
+ commit();
+ stmt2.executeUpdate("update testClob set el = 'smurfball' where b = 1");
+
stmt2.close();
conn2.commit();
conn2.close();
@@ -2266,14 +2276,19 @@
"update testBlob set b = b + 1 where b = 10000");
stmt.close();
stmt2.close();
+ conn2.rollback();
conn2.close();
fail("FAIL - should have gotten lock timeout");
} catch (SQLException se) {
checkException(LOCK_TIMEOUT, se);
}
+
+ // Test that update goes through after the transaction is committed
+ commit();
+ stmt2.executeUpdate("update testBlob set b = b + 1 where b = 10000");
+
stmt.close();
stmt2.close();
- commit();
conn2.commit();
conn2.close();
}
@@ -2325,11 +2340,16 @@
stmt2.executeUpdate("update testBlob set el = null where b = 1");
stmt2.close();
stmt.close();
+ conn2.rollback();
conn2.close();
fail("FAIL - statement should timeout");
} catch (SQLException se) {
checkException(LOCK_TIMEOUT, se);
}
+ // Test that update goes through after the transaction is committed
+ commit();
+ stmt2.executeUpdate("update testBlob set el = null where b = 1");
+
stmt2.close();
conn2.commit();
stmt.close();