On Apr 26, 2007, at 2:10 AM, tbee wrote:


Is it possible to provide an actual JDBC connection instead of connect
parameters?

You can supply the datasource instance in a PersistenceUnitInfo, but I certainly hope you can't provide a connection.

The business model I'm trying to construct will work inside an existing application which does direct JDBC. There is already a connection open and it would be a waste of resource to have two. I can always hack together a special Driver for this. Another solution would be to use the connection of
OpenJPA.

Are you running inside a javaee app server? (not standalone tomcat) If so there's a very good chance that all the connection handles obtained within the same jta transaction actually use the same physical connection to the database. Geronimo certainly does this.

One concern: how many actual JDBC connections are opened during a run. I assume that only one is opened and that the JPA "transaction" concept is not directly related to the JDBC transactions. That JDBC transactions are only
used during a JPA transaction's commit phase.

If you use table based "sequences" and supply a non-jta-datasource as well as a jta datasource, typically 2 connections will be used. However, if you are in an environment that does connection pooling this won't make much difference.

Hope this helps
david jencks


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