Thursday, October 07, 2004

Using READ_UNCOMMITTED in CMP2.0

(Answers)From: Paul Ilechko
Newsgroups: ibm.software.websphere.application-server

I need to use the transaction isolation level of READ_UNCOMMITTED for some of my CMP2.0 beans. The "EJB deployment descriptor Editor" is not allowing to define an isolation level for CMP2.0. Seems like that the only way to set it is to use access intent. But even with access intent of wsOptimisticRead, I get the isolation level of ReadCommitted only (for DB2).
I am not going to update this datasource ever and also don't mind dirty reads. Is there a way I can do this in WAS 5.1?
Yeah, this is one of the reasons I don't like access intents - the defaults don't make any sense, and some of the combinations of isolation level and locking strategty that you really need (such as pessimistic locking with READ_COMMITTED) aren't even possible.
May I ask why you are even using CMP EJB here? CMP is quite good for doing CRUD operations on a single row, and really pretty poor at dealing with queries, lists and larger result sets. If you're mostly dealing with the latter, you're better off using straight JDBC.

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