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From "Patrick Linskey (JIRA)" <>
Subject [jira] Commented: (OPENJPA-182) db2 update lock syntax WITH <isolation> USE AND KEEP UPDATE LOCKS
Date Thu, 05 Apr 2007 00:45:32 GMT


Patrick Linskey commented on OPENJPA-182:

It's probably worth noting that everything in the FetchPlan is configurable via the Query.setHint()
APIs. My earlier theoretical test case would become:

Query q = em.createQuery(...);
q.setHint("openjpa.FetchPlan.IsolationLevel", Connection.TRANSACTION_SERIALIZABLE);
q.setHint("openjpa.FetchPlan.ReadLockMode", LockModeType.WRITE);
List l = q.getResultList(); 

In other words, if we use the patch that I attached (or something like it), we will end up
with strong typing, API alignment with similar concepts, and dynamic accessibility both in
terms of Query.setHint() and @QueryHints annotations / query-hint XML.

> db2 update lock syntax  WITH <isolation> USE AND KEEP UPDATE LOCKS
> ------------------------------------------------------------------
>                 Key: OPENJPA-182
>                 URL:
>             Project: OpenJPA
>          Issue Type: New Feature
>          Components: jdbc
>         Environment: db2 database driver for zOS, AS400, Unix, Windows, Linux
>            Reporter: David Wisneski
>         Assigned To: David Wisneski
>         Attachments: OPENJPA-182.patch, openJPA182.patch
> A while back we changed the syntax of update locking from FOR UPDATE OF  to  WITH RS
USE AND KEEP UPDATE LOCKS.   Additional changes are required because 
> 1.  if isolation=serializable is configured, then the syntax should be  WITH RR USE AND
> 2.  when using DB2/400 on iSeries machines, the syntax is WITH RS USE AND KEEP EXCLUSIVE
LOCKS  or WITH RR USE AND KEEP EXCLUSIVE LOCKS because DB2/400 only supports read or exclusive
> 3.  DB2 supports both a FETCH FIRST  ROWS and update LOCKS clauses.
> So we change supportsLockingWithSelectRange = true in the AbstractDB2Dictionary class
and change the DB2Dictionary to append the correct LOCKS syntax depending on vendor, release
and isolation level.

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