| From: | Josh Berkus <josh(at)agliodbs(dot)com> |
|---|---|
| To: | Simon Riggs <simon(at)2ndQuadrant(dot)com> |
| Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Greg Stark <gsstark(at)mit(dot)edu>, Nicolas Barbier <nicolas(dot)barbier(at)gmail(dot)com>, Markus Wanner <markus(at)bluegap(dot)ch>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: Deadlock bug |
| Date: | 2010-08-25 22:56:05 |
| Message-ID: | 4C759F85.2000807@agliodbs.com |
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| Lists: | pgsql-hackers |
On 8/25/10 1:35 PM, Simon Riggs wrote:
> If the row is "key share" locked (as opposed to "tuple share" locks we
> already have), then an UPDATE would only work if it was a non-HOT
> UPDATE. Yes, that would save us some effort in working out whether to
> allow the UPDATE or not. It *is* more restrictive than strictly
> necessary, but much better than the current situation. So at least we
> know that part of it has an easy solution.
I agree that this would be an improvement.
It still has the issue of being baffling to users (why did I get a
deadlock this time, and not THAT time?) but current behavior has that
problem. Heck, current behavior is often baffling to *me*.
The other thing which came out of this incident (and many user reports)
is the rather extreme opacity of our locking information, despite the
improvements of the last 2 versions. However, I don't have a proposal
on how that should be fixed .... yet.
--
-- Josh Berkus
PostgreSQL Experts Inc.
http://www.pgexperts.com
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