| From: | Simon Riggs <simon(at)2ndquadrant(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Kris Kiger <kris(at)musicrebellion(dot)com>, pgsql-admin(at)postgresql(dot)org |
| Subject: | Re: Concurrency |
| Date: | 2005-05-09 21:38:35 |
| Message-ID: | 1115674715.3830.78.camel@localhost.localdomain |
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| Lists: | pgsql-admin |
On Mon, 2005-05-09 at 15:18 -0400, Tom Lane wrote:
> Simon Riggs <simon(at)2ndquadrant(dot)com> writes:
> > On Mon, 2005-05-09 at 12:21 -0500, Kris Kiger wrote:
> >> Quick question. I lock a table, call it table X, and then issue two
> >> updates on that table. The two updates are left waiting. I then unlock
> >> the table. The two updates go through. My question is, is there a
> >> predictable way to determine which query will be executed first?
>
> > The lock queue is served in FIFO sequence.
>
> ... usually. We will promote later arrivals in front of older ones if
> the alternative would be a deadlock (eg, the later one already holds
> some lock that would block the earlier one).
Thats part of deadlock detection? I had thought we just blew one away...
Thanks,
Best Regards, Simon Riggs
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