| From: | Richard Huxton <dev(at)archonet(dot)com> |
|---|---|
| To: | cgg007(at)yahoo(dot)com, pgsql-sql(at)postgresql(dot)org |
| Subject: | Re: FIFO Queue Problems |
| Date: | 2002-11-01 16:20:59 |
| Message-ID: | 200211011620.59439.dev@archonet.com |
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| Thread: | |
| Lists: | pgsql-general pgsql-sql |
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 want.
This means that 1 time in 1000 your query will fail and need to be retried.
HTH
--
Richard Huxton
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