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From Daniel John Debrunner <...@debrunners.com>
Subject Re: [jira] Commented: (DERBY-231) "FOR UPDATE" required for updatable result set to work
Date Fri, 28 Oct 2005 14:23:57 GMT
Dag H. Wanvik wrote:

> Hi,
> Andreas> >   2) Applications use the FOR UPDATE clause to control locking for
> Andreas> > future updates with read only ResultSets.
> Andreas> >
> Andreas> 
> Andreas> Note currently it throws an exception if the statement is not updatable 
> Andreas> i.e contains a join or order by.
> I guess what you mean here is that the FOR UPDATE is not in general
> available as a means for locking for future updates.
> To Dan's point, my tests indicate that the current Derby
> implementation for forward-only updatable result sets only sets a row
> update lock while on the current row.

I think that's only true for read committed isolation level, in higher
levels the update lock will be there until end of transaction. So I
guess this use is only useful with those isolation levels.


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