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From: Richard Huxton <dev@archonet.com>
Organization: Archonet Ltd
To: cgg007@yahoo.com, pgsql-sql@postgresql.org
Subject: Re: FIFO Queue Problems
Date: Fri, 1 Nov 2002 16:20:59 +0000
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On Friday 01 Nov 2002 2:56 pm, Chris Gamache wrote:
> I'm having a race condition with a FIFO queue program that I've created...

> I have a program that claims a row for itself

[code sample]

> The problem occurrs when two of the processes grab the exact same row at
> the exact same instant. It happens roughly 1 out of 1000 times. I'm not
> sure if setting the transactions to serializable would fix the problem
> since it occurrs between different postmasters.
>
> My experience with Views and Triggers is minimal. Would they even help?
> Could someone suggest a better FIFO queue method?

Check out SELECT FOR UPDATE - this locks the row and should do what you wan=
t.=20
This means that 1 time in 1000 your query will fail and need to be retried.

HTH
--=20
  Richard Huxton