Hello, Im working with SEAM 1.2.1 and I have two datasources: one is from a Postgres database (and works fine) and the other one is for a MySQL database ('WP7Datasource', which doesn't work). The problem is that when I start JBoss i get this error: 16:58:20,968 INFO [SessionFactoryImpl] building session factory 17:08:39,718 WARN [ServiceController] Problem starting service persistence.units:ear=medieq-aqua.ear,jar=medieq-aqua.jar,unitName=WP7Datasource javax.persistence.PersistenceException: org.hibernate.MappingException: could not instantiate id generator at org.hibernate.ejb.Ejb3Configuration.buildEntityManagerFactory(Ejb3Configuration.java:695) at org.hibernate.ejb.HibernatePersistence.createContainerEntityManagerFactory(HibernatePersistence.java:127) at org.jboss.ejb3.entity.PersistenceUnitDeployment.start(PersistenceUnitDeployment.java:264) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) ... Caused by: org.hibernate.MappingException: could not instantiate id generator at org.hibernate.id.IdentifierGeneratorFactory.create(IdentifierGeneratorFactory.java:98) at org.hibernate.mapping.SimpleValue.createIdentifierGenerator(SimpleValue.java:152) at org.hibernate.impl.SessionFactoryImpl.(SessionFactoryImpl.java:192) at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1218) at org.hibernate.ejb.Ejb3Configuration.buildEntityManagerFactory(Ejb3Configuration.java:688) ... 147 more Caused by: org.hibernate.MappingException: Dialect does not support sequences at org.hibernate.dialect.Dialect.getSequenceNextValString(Dialect.java:570) at org.hibernate.id.SequenceGenerator.configure(SequenceGenerator.java:65) at org.hibernate.id.SequenceHiLoGenerator.configure(SequenceHiLoGenerator.java:43) at org.hibernate.id.IdentifierGeneratorFactory.create(IdentifierGeneratorFactory.java:94) .... the datasources are defined here: <?xml version="1.0" encoding="UTF-8"?> | <datasources> | <local-tx-datasource> | <jndi-name>medieqDatasource</jndi-name> | <connection-url> | jdbc:postgresql://localhost:5432/medieqdev | </connection-url> | <driver-class>org.postgresql.Driver</driver-class> | <user-name>****</user-name> | <password>****</password> | <connection-property name="char.encoding"> | UTF-8 | </connection-property> | <transaction-isolation> | TRANSACTION_READ_COMMITTED | </transaction-isolation> | <min-pool-size>25</min-pool-size> | <max-pool-size>100</max-pool-size> | <blocking-timeout-millis>5000</blocking-timeout-millis> | <idle-timeout-minutes>15</idle-timeout-minutes> | <prepared-statement-cache-size> | 75 | </prepared-statement-cache-size> | </local-tx-datasource> | | <!-- add datasource for UMLS MYSQL database (Manuel Fidalgo)--> | <local-tx-datasource> | <jndi-name>WP7Datasource</jndi-name> | <connection-url>jdbc:mysql://localhost/umls</connection-url> | <driver-class>com.mysql.jdbc.Driver</driver-class> | <user-name>***</user-name> | <password>***</password> | <connection-property name="char.encoding">UTF-8</connection-property> | <transaction-isolation>TRANSACTION_READ_COMMITTED</transaction-isolation> | <min-pool-size>25</min-pool-size> | <max-pool-size>100</max-pool-size> | <blocking-timeout-millis>5000</blocking-timeout-millis> | <idle-timeout-minutes>15</idle-timeout-minutes> | <prepared-statement-cache-size>75</prepared-statement-cache-size> | <metadata> <type-mapping>mySQL</type-mapping></metadata> | </local-tx-datasource> | </datasources> and the persistence.xml is this: <persistence> | <persistence-unit name="medieqDatasource"> | <provider>org.hibernate.ejb.HibernatePersistence</provider> | <jta-data-source>java:/medieqDatasource</jta-data-source> | <properties> | <!-- create-drop --> | <property name="hibernate.hbm2ddl.auto" value="validate"/> | <property name="hibernate.show_sql" value="true"/> | <!-- These are the default for JBoss EJB3, but not for HEM: /--> | <property name="hibernate.cache.provider_class" value="org.hibernate.cache.HashtableCacheProvider"/> | <property name="hibernate.transaction.manager_lookup_class" value="org.hibernate.transaction.JBossTransactionManagerLookup"/> | <property name="jboss.entity.manager.factory.jndi.name" value="java:/medieqEntityManagerFactory"/> | </properties> | </persistence-unit> | | <!-- MySQL UMLS database Manuel Fidalgo --> | <persistence-unit name="WP7Datasource"> | <provider>org.hibernate.ejb.HibernatePersistence</provider> | <jta-data-source>java:/WP7Datasource</jta-data-source> | <properties> | <property name="hibernate.hbm2ddl.auto" value="validate" /> | <property name="hibernate.cache.use_query_cache" value="true" /> | <property name="hibernate.show_sql" value="true" /> | <property name="hibernate.dialect" value="org.hibernate.dialect.MySQL5Dialect" /> | <property name="hibernate.connection.username" value="***" /> | <property name="hibernate.connection.password" value="***" /> | <property name="hibernate.connection.driver_class" value="com.mysql.jdbc.Driver" /> | <property name="hibernate.connection.url" value="jdbc:mysql://localhost/umls" /> | <property name="jboss.entity.manager.factory.jndi.name" value="java:/WP7EntityManagerFactory" /> | <property name="hibernate.jdbc.use_get_generated_keys" value="false" /> | </properties> | </persistence-unit> | </persistence> Both databases are working and I can connect to them via JDBC. I have no entities for the MySQL database but is should work...I think that the problem is that the configuration forces MySQL to use id generators and it doesnt work but I don't know why it uses this generators and if I could turn off this feature (only for MySQL)... Any help will be apreciated... thanks View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4100758#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...