[jboss-user] [EJB 3.0] - Re: Problem using SequenceGenerator

bryan_castillo do-not-reply at jboss.com
Thu Jul 27 12:34:35 EDT 2006

I don't think my problem is database related.  

Arno, did you see if the next value of your postgres sequence corresponded to the value actually inserted?

I launched jboss in debug mode and attached eclipse remotely to it and found the hibernate class which is applying modifications to the value returned from the database sequence.

The generated id is being generated by org.hibernate.id.SequenceHiLoGenerator.  Here is the method.

	public synchronized Serializable generate(SessionImplementor session, Object obj) 
  | 	throws HibernateException {
  | 		if (maxLo < 1) {
  | 			//keep the behavior consistent even for boundary usages
  | 			long val = ( (Number) super.generate(session, obj) ).longValue();
  | 			if (val == 0) val = ( (Number) super.generate(session, obj) ).longValue();
  | 			return IdentifierGeneratorFactory.createNumber( val, returnClass );
  | 		}
  | 		if ( lo>maxLo ) {
  | 			long hival = ( (Number) super.generate(session, obj) ).longValue();
  | 			lo = (hival == 0) ? 1 : 0;
  | 			hi = hival * ( maxLo+1 );
  | 			if ( log.isDebugEnabled() )
  | 				log.debug("new hi value: " + hival);
  | 		}
  | 		return IdentifierGeneratorFactory.createNumber( hi + lo++, returnClass );
  | 	}

I would like to have the id, generated by org.hibernate.id.SequenceGenerator instead of org.hibernate.id.SequenceHiLoGenerator.   Is there a way to specify the class which should be used as the generator?

I read some of the comments for both of these generators and it looks like the HiLo version is used for performance. I believe it is able to reserve chunks of sequence numbers at a time.  But I was trying to created entity beans for an existing database and still fit the same sequence/id usage pattern of the old code.

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