Platform Specific Issues

Platform Specific Issues
I get an OutOfMemoryException when I redeploy on Tomcat!
Can I use Hibernate with JDK 1.3?
Hibernate doesn't work with MySQL!
Hibernate expects my JDBC driver to support JDBC2 but it doesn't!
My JDBC driver supports batch updates. How come Hibernate doesn't enable them by default?
Hibernate doesn't work with my MS SQL 2000 JDBC driver?
Are there known issues with Interbase / Firebird?
I'm having problems with Weblogic Server!
After a while, Oracle throws this exception: too many open cursors
MySQL throws an exception: Cannot disable AUTO_COMMIT
Tomcat throws java.lang.UnsupportedOperationException when fetching a JDBC connection
JBoss AS complains about unclosed connections?

I get an OutOfMemoryException when I redeploy on Tomcat!
This is common and not the fault of Hibernate or anything Hibernate does. Hibernate has no leaking ThreadLocal variables, no classloader magic, nothing else that has ever been identified as causing this and could be somehow fixed in Hibernate. Tomcat's reloading of the web contexts doesn't work reliably with other libraries (such as Struts, etc), the reasons are often found in Tomcat, Classloaders, or JVM bugs. Please don't post any questions about this on the Hibernate forums, or on the Hibernate developer list. Ask on the Tomcat users list. If you need hot redployment to work immediately, use Tomcat inside JBoss application server.
Can I use Hibernate with JDK 1.3?
Yes, but the distributed binaries are compiled for JDK 1.4 and newer. You will have to recompile Hibernate from source (type 'ant' in the distribution directory). This probably fails, as some of the dependencies of Hibernate have been compiled or are only available for JDK 1.4 and newer. However, users reported success after they found replacements for these dependencies.
Hibernate doesn't work with MySQL!
The MySQL Server 4.1.12 RPM delivered with Mandriva Linux 2006 breaks prepared statements. This can be solved by either adding "useServerPrepStmts=false" to the MySQL connection string in the Hibernate configuration file or by using an unbroken original MySQL Server package. http://bugs.mysql.com/bug.php?id=14910
Hibernate expects my JDBC driver to support JDBC2 but it doesn't!
Set hibernate.jdbc.batch_size=0
hibernate.jdbc.use_scrollable_resultsets=false
or upgrade your driver to the latest version. Hibernate chooses sensible default values for these properties, based upon your SQL dialect.
My JDBC driver supports batch updates. How come Hibernate doesn't enable them by default?
Batch updates seem to be cause problems for some JDBC drivers that claim to support them. We found that batch updates should be disabled for DB2 and Sybase.
Hibernate doesn't work with my MS SQL 2000 JDBC driver?
(Glen Stampoultzis)
If you're using Hibernate with the Microsoft SQL Server 2000 JDBC driver chances are you'll run into this problem:java.sql.SQLException: [Microsoft][SQLServer 2000 Driver for JDBC]
Can't start a cloned connection while in manual transaction mode.
Simply add SelectMethod=Cursor; to your connection string. There's a MS knowledge base article with more information. The Microsoft SQL Server 2005 JDBC driver has been certified by JBoss Inc.
Are there known issues with Interbase / Firebird?
(Michael Jakl)
Yes. Due to some limitations in Interbase / Firebird we must use some workarounds:
Always set the size of your statement cache to zero (hibernate.statement_cache.size or hibernate.c3p0.max_statements)
If you are altering tables you should be in single user mode. This can be achieved by running gfix -shut. It's also sufficient to have only one database connection open (eg. immediately after starting the application). If more than one connection is open, you will see errors like "table is in use". To restart your database use gfix -online.
I'm having problems with Weblogic Server!
If you get CharScanner; panic: ClassNotFoundException: org.hibernate.hql.ast.HqlToken - Hibernate 3.x includes a new query parser that doesn't run on Weblogic - the reason is a packaging error of ANTLR in Weblogic's boot classpath. Read the section in the Hibernate3 Migration Guide.
If you have a = javax.naming.NoInitialContextException=, this seems to solve it for Weblogic 8.1, in your Hibernate configuration:t3://localhost:7001
weblogic.jndi.WLInitialContextFactory
The JNDI implementation in WebLogic Server does not appear to support the Referenceable interface, and exhibits some rather strange behaviour when binding Serializable objects. Please direct complaints to BEA. This might affect only older versions of Weblogic.
Workarounds include using a different JNDI implementation (eg. Sun's FSContext) or using some other means of obtaining a SessionFactory.
See also Mathias' Blog!
The forum users believe there's some problem if you do it the regular way like most app server. Therefore, try the following (which works for me). Use a WLS Startup class to bind Hibernate Session Factory object in WLS JNDI. Here's an excerpt of a possible code:public class WLSStartup implements T3StartupDef
{
public static final String SESSION_FACTORY_JNDI = "hibernate";
public static final String URL = "t3://localhost:7001";
/**
* Called by WebLogic server upon startup. This is where everything should
* be initialzed.
*
* @param name the JNDI name of this class
* @param args any input parameters
*
* @return the status.
*
* @throws Exception in case of any error
*/
public String startup( String name, Hashtable args ) throws Exception
{
String METHOD_NAME = "startup ";
// Bind the various Hibernate Object to the Weblogic JNDI
try
{
log ( METHOD_NAME + " Going to bind Hibernate object. " );
doBind( );
log ( METHOD_NAME + " Bound Hibernate object!" );
}
catch ( Exception exception )
{
log ( METHOD_NAME + " Exception while binding Hibernate Object to Weblogic JNDI" );
exception.printStackTrace ( );
}
return "WLS Startup completed successfully";
}
/**
* Performs Hibernate objects to Weblogic JNDI Namespace bindings.
* It gets the initial context and binds the Hibernate objects to it.
*
* @param None
* @throws Exception in case of any errors
*/
private static void doBind( ) throws Exception
{
Properties environment = null;
InitialContext context = null;
try
{
//Properties for storing JNDI configuration information
environment = new Properties( );
//Add initial context factory
environment.put( Context.INITIAL_CONTEXT_FACTORY,"weblogic.jndi.WLInitialContextFactory");
environment.put( Context.PROVIDER_URL, URL );
log( "Constructing an Initial Directory Context object" );
context = new InitialContext( environment );
Datastore ds = Hibernate.createDatastore();
SessionFactory factory = ds.buildSessionFactory();
if (factory == null)
throw new Exception("SessionFactory cannot be built?!");

try
{
if( context.lookup(SESSION_FACTORY_JNDI ) != null )
context.rebind(SESSION_FACTORY_JNDI, factory );
else
context.bind(SESSION_FACTORY_JNDI, factory );
}
catch ( NamingException nameEx )
{
context.bind(SESSION_FACTORY_JNDI, factory );
}
}
catch ( NamingException nameExp )
{
throw new Exception( "NamingException: " + nameExp.getMessage( ));
}
catch( Exception excp )
{
throw excp;
}
finally
{
if( context != null )
{
try
{
context.close( );
context = null;
}
catch ( NamingException nameExp )
{
throw new Exception( "NamingException for context close: " nameExp.getMessage( ));
}
}
environment = null;
}
}
Jar up the relevant Hibernate jar files and configure this Startup class under WLS console.
Then at your JNDI client (Servlet or EJBs for example) you can have a code similar to this excerpt below: -Object objref;
Context context;
Hibernate.configure();
//The usual WLS JNDI context
context = getInitialContext();
objref = context.lookup(WLSStartup.SESSION_FACTORY_JNDI);
sessionFac = (SessionFactory) PortableRemoteObject.narrow(objref, SessionFactory.class);
if sessionFac == null)
throw new Exception("Null SessionFactory found?!");
Works great with Struts 1.1 on WLS 6.X and 7.X. I've tested by writing some subclass relationship data into Oracle 8i!
Any questions can be directed to simon@see-consulting.com.
After a while, Oracle throws this exception: too many open cursors
The Oracle JDBC driver doesn't much like to have its prepared statements cached. Disable PreparedStatement caching for the connection pool.
MySQL throws an exception: Cannot disable AUTO_COMMIT
Download the latest MySQL driver.
Tomcat throws java.lang.UnsupportedOperationException when fetching a JDBC connection
In Tomcat (maybe other situations) if you are using the built-in DBCP to as a JNDI datasource, be sure that you do not specify hibernate.connection.username or hibernate.connection.password in either hibernate.cfg.xml or hibernate.properties. DBCP does not implement the version of Datasource.getConnection() that takes a username and password.
JBoss AS complains about unclosed connections?
If you get the message "[org.jboss.resource.connectionmanager.CachedConnectionManager] Closing a connection for you. Please close them yourself: org.jboss.resource.adapter.jdbc.WrappedConnection" you are missing a configuration setting, hibernate.connection.release_mode - set it to auto or read the reference documentation about it.

NEW COMMENT
After a while, Oracle throws this exception: too many open...
30 Dec 2003, 17:06
dominikroblek
We are successfully using Hibernate with Oracle JDBC driver with
prepared statement cache enabled. We had to raise open cursor limit in
Oracle database as each cached prepared statement keeps one open cursor
on the database. Ask you DBA for assistance.

I need more Info about issues with Interbase / Firebird?
11 May 2005, 11:13
erick_77
Hi,
I am new using Hibernate. I tested the auctions example of Hibernate
using PostgresSQL as database, and it ran witout any trouble. But now I
need to test it with firebird, when I run the build.bat It creates the
tables but at the moment that it starts to alter table it displays
errors that tables are in use. Example:
[java] 16:31:22,869 DEBUG SchemaExport:162 - alter table
AuctionItem add constraint FK522A9BD61107FE9B foreig
key (seller) references AuctionUser
[java] 16:31:22,929 ERROR SchemaExport:168 - Unsuccessful: alter
table AuctionItem add constraint FK522A9BD61
07FE9B foreign key (seller) references AuctionUser
[java] 16:31:22,929 ERROR SchemaExport:169 - Resource Exception.
unsuccessful metadata update
[java] object AUCTIONUSER is in use
[java] Reason: unsuccessful metadata update
[java] object AUCTIONUSER is in use
I read in this page something about this issue. And the solution is that
I need to execute the firebird's gfix command. I would like to get more
information about this issue, please be more specific with your answer
or if you have another alternative way to solve it.
Thanks.

Incorrect link for JSQL
23 Sep 2005, 07:22
geofft
The link provided for JSQL is http://www.j-netdirect.com when in fact
it should be http://www.jnetdirect.com

Re: After a while, Oracle throws this exception: too many open..
20 Apr 2006, 08:10
bworwood
POST QUESTIONS ON THE FORUM! COMMENTS HERE SHOULD ADD VALUE TO THE
PAGE!On 30 Dec 2003 17:06, dominikroblek wrote:
>We are successfully using Hibernate with Oracle JDBC driver with
>prepared statement cache enabled. We had to raise open cursor limit in
>Oracle database as each cached prepared statement keeps one open
cursor
>on the database. Ask you DBA for assistance.
I am having a similar problem - open cursors are not being cleared.
Did you get over your issue?

DB2 ClassCastException when using JDBC batches
08 Sep 2006, 13:08
iamjvn
Be careful when using JDBC batch settings larger than 0.
DB2 driver with a JDBC batch size other than 0 may cause a
ClassCastException.
Caused by: java.lang.ClassCastException: java.lang.Integer
at com.ibm.db2.jcc.a.jb.a(jb.java:1068)
at com.ibm.db2.jcc.a.jb.a(jb.java:792)
at com.ibm.db2.jcc.a.jb.a(jb.java:163)
at com.ibm.db2.jcc.a.tb.a(tb.java:220)
at com.ibm.db2.jcc.b.ad.a(ad.java:1625)
at com.ibm.db2.jcc.b.ad.b(ad.java:2725)
at com.ibm.db2.jcc.b.ad.a(ad.java:2632)
at com.ibm.db2.jcc.b.ad.executeBatch(ad.java:2444)
at com.ibm.db2.jcc.b.ad.executeBatch(ad.java:1329)
at
com.mchange.v2.c3p0.impl.NewProxyPreparedStatement.executeBatch(NewProxyPreparedStatement.java:1723)
hibernate.cfg.xml
-----------------
...
0
...

Re: After a while, Oracle throws this exception: too many open..
25 Oct 2006, 20:06
caili314
POST QUESTIONS ON THE FORUM! COMMENTS HERE SHOULD ADD VALUE TO THE
PAGE!On 20 Apr 2006 08:10, bworwood wrote:
>POST QUESTIONS ON THE FORUM! COMMENTS HERE SHOULD ADD VALUE TO THE
>PAGE!On 30 Dec 2003 17:06, dominikroblek wrote:
>>We are successfully using Hibernate with Oracle JDBC driver with
>>prepared statement cache enabled. We had to raise open cursor limit in
>>Oracle database as each cached prepared statement keeps one open
>cursor
>>on the database. Ask you DBA for assistance.
>I am having a similar problem - open cursors are not being cleared.
>Did you get over your issue?
I ran into the same problem when using DBCP connection provider in
Hibernate 2.1.2. Traced into
net.sf.hibernate.connection.DBCPConnectionProvider, I found the
construction of statementPool didn't pass in maxTotal parameter, which
is used by GenericKeyedObjectPoolFactory to determine when to clear the
pool content. So the solutions can be either to pass in this parameter
or to disable statement pool by simply setting statemPool to null. Both
work!

Incorrect FAQ regarding Batch updates against DB2
23 Mar 2007, 00:00
anshuld
This FAQ above (#ABCD6) regarding batch
updates should be disabled against DB2 is incorrect. Batch update works
fine when using IBM DB2 JDBC driver shipped with version 8 and version
9. Batch updates should be enabled because it provides performance
advantages to application using hibernate against DB2.
In another thread (http://www.hibernate.org/120.741.html) it shows a
stack trace with ClassCastException. This only happens if type changes
between batch elements. This can be avoided by setting connection
property deferPrepares to false. This bug was also fixed in the driver
that was shipped in early 2006.

DB2 and Blobs
20 May 2008, 21:59
sgwood
Working with Hibernate + Blobs against DB2 databases, you need to be
careful with the JDBC connection settings.
When reading the blob, you can get:
com.ibm.db2.jcc.b.SqlException: [jcc][10120][11936][3.50.152] Invalid
operation: Lob is closed. ERRORCODE=-4470, SQLSTATE=null
at com.ibm.db2.jcc.b.wc.a(wc.java:55)
at com.ibm.db2.jcc.b.wc.a(wc.java:93)
at com.ibm.db2.jcc.b.rd.d(rd.java:67)
at com.ibm.db2.jcc.b.sd.w(sd.java:202)
at com.ibm.db2.jcc.b.sd.getBinaryStream(sd.java:107)
at
org.hibernate.lob.SerializableBlob.getBinaryStream(SerializableBlob.java:39)
This was with DB2 9.5 and the db2jcc driver.
The solution was to follow the advice of
http://www.ibm.com/developerworks/forums/thread.jspa?messageID=14053553
getting to a JDBC connect string like:
jdbc:db2://localhost:50000/testDB:fullyMaterializeLobData=true;fullyMaterializeInputStreams=true;progressiveStreaming=2;progresssiveLocators=2;