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From Perrin Harkins <>
Subject Re: Apache::Session::Store::Postgres FOR UPDATE problems
Date Mon, 02 May 2005 22:27:06 GMT
On Mon, 2005-05-02 at 15:08 -0700, Jeffrey W. Baker wrote:
> It is possible that the FOR UPDATE is spurious.  It signals to the
> database system that this transaction intends to write that row.  With
> PostgreSQL's MVCC transaction isolation system, it's probably not
> necessary and may be causing problems.

I'd say it's necessary if you want mutual exclusion, since MVCC will not
prevent lost updates.  Not everyone needs mutual exclusion, so it could
be made optional, or tied to a particular locking module selection.

- Perrin

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