From: Joe Carr <joe.carr@gmail.com>
To: pgsql-sql@postgresql.org
Subject: Correct usage of FOR UPDATE?
Date: Thu, 9 Dec 2010 14:29:42 -0500
Message-ID: <AANLkTin1qX+ZSOGsvdY7RH0dkTEkxth-XaAy2DSA8HTd@mail.gmail.com> (raw)
Hello,
I have a simple table-based queue system, and I'd looking for some advice on
improving my dequeue function. it boils down to:
SELECT id
FROM queue
WHERE <whereclause>
FOR UPDATE NOWAIT;
which works well, in that no item gets dequeued more that once. The issue,
however is that when a contention occurs, the error "could not obtain lock
on row in relation" is raised.
Is there a way that I can rewrite this so that when a contention occurs,
there is no error? I would like the "winning" process to lock the row, and
the "losing" process to select null rather than raise the rowlock error.
thanks beforehand for any help!
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To: pgsql-sql@postgresql.org
Cc: joe.carr@gmail.com
Subject: Re: Correct usage of FOR UPDATE?
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