[hibernate-issues] [Hibernate-JIRA] Created: (HHH-3523) org.hibernate.id.enhanced.SequenceStyleGenerator causes org.hibernate.MappingException with SAPDB and DB2Dialect

[Damir Malenicic (JIRA)]

org.hibernate.id.enhanced.SequenceStyleGenerator causes org.hibernate.MappingException with SAPDB and DB2Dialect
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                 Key: HHH-3523
                 URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-3523
             Project: Hibernate Core
          Issue Type: Bug
          Components: core
    Affects Versions: 3.3.1
         Environment: Hibernate 3.3.1.GA
Generation of DDL scripts for DB2Dialect and SAPDBDialect
            Reporter: Damir Malenicic
         Attachments: db2-sapdb-bug.zip

While generating DDL scripts for mapping files that declare id <generator class="org.hibernate.id.enhanced.SequenceStyleGenerator"> the following exception is thrown:
org.hibernate.MappingException: Dialect does not support pooled sequences
	at org.hibernate.dialect.Dialect.getCreateSequenceString(Dialect.java:701)
	at org.hibernate.dialect.Dialect.getCreateSequenceStrings(Dialect.java:659)
	at org.hibernate.id.enhanced.SequenceStructure.sqlCreateStrings(SequenceStructure.java:139)
	at org.hibernate.id.enhanced.SequenceStyleGenerator.sqlCreateStrings(SequenceStyleGenerator.java:328)
	at org.hibernate.cfg.Configuration.generateSchemaCreationScript(Configuration.java:945)
	at org.hibernate.tool.hbm2ddl.SchemaExport.<init>(SchemaExport.java:129)
	at org.hibernate.tool.hbm2ddl.SchemaExport.<init>(SchemaExport.java:91)

I suspect the cause is in 
org.hibernate.dialect.Dialect#getCreateSequenceString(String sequenceName, int initialValue, int incrementSize)
		if ( supportsPooledSequences() ) {
			return getCreateSequenceString( sequenceName ) + " start with " + initialValue + " increment by " + incrementSize;
		}
		throw new MappingException( "Dialect does not support pooled sequences" );

This call requires not just that dialect supports sequences but that dialect supports pooled sequences.

But the algorithm that tries to determine whether the table should be used to emulate the sequence lets the dialects that supports sequences but not pooled sequences to slip through. It looks like the DB2 and SAPDB dialects fail in this category because of:

org.hibernate.id.enhanced.SequenceStyleGenerator#configure(Type type, Properties params, Dialect dialect)
...
		if ( dialect.supportsSequences() && !forceTableUse ) {
			if ( OptimizerFactory.POOL.equals( optimizationStrategy ) && !dialect.supportsPooledSequences() ) {
				forceTableUse = true;
				log.info(
						"Forcing table use for sequence-style generator due to pooled optimizer selection where db does not support pooled sequences"
				);
			}
		}

To workaround the problem I have created my generator that overrides SequenceStyleGenerator#configure, somethng like:
    public void configure(Type type, Properties params, Dialect dialect) throws MappingException {
        if (dialect.supportsSequences() && !dialect.supportsPooledSequences()) {
            params.setProperty(FORCE_TBL_PARAM, "true");
        }
        super.configure(type, params, dialect);

Attached is a zip file with a small maven project with unit-test that replicates the problem. It generates DDL for different databases: Hipersonic, Derby, Oracle, MySql, PostgreSQL, MSSQL, DB2, and SAPDB. The data-model contains 2 tables Person and Event in many-to-many relation.


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