Re: First steps with 8.3 and autovacuum launcher

From: Alvaro Herrera <alvherre(at)commandprompt(dot)com>
To: Simon Riggs <simon(at)2ndquadrant(dot)com>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Gregory Stark <stark(at)enterprisedb(dot)com>, Guillaume Smet <guillaume(dot)smet(at)gmail(dot)com>, "Matthew T(dot) O'Connor" <matthew(at)zeut(dot)net>, Heikki Linnakangas <heikki(at)enterprisedb(dot)com>, Stefan Kaltenbrunner <stefan(at)kaltenbrunner(dot)cc>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: First steps with 8.3 and autovacuum launcher
Date: 2007-10-04 21:33:42
Message-ID: 20071004213342.GE28896@alvh.no-ip.org
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Simon Riggs escribió:

> Seems like we don't need to mess with the deadlock checker itself.
>
> We can rely on the process at the head of the lock wait queue to sort
> this out for us. So all we need do is look at the isAutovacuum flag on
> the process that is holding the lock we're waiting on. If it isn't an
> autoANALYZE we can carry on with the main deadlock check. We just need a
> new kind of deadlock state to handle this, then let ProcSleep send
> SIGINT to the autoANALYZE and then go back to sleep, waiting to be
> reawoken when the auotANALYZE aborts.

Ok, I think this makes sense.

I can offer the following patch -- it makes it possible to determine
whether an autovacuum process is doing analyze or not, by comparing the
PGPROC of the running WorkerInfo list (the list has at most
max_autovacuum_workers entries, so this is better than trolling
ProcGlobal).

--
Alvaro Herrera http://www.CommandPrompt.com/
PostgreSQL Replication, Consulting, Custom Development, 24x7 support

Attachment Content-Type Size
autovac-is-analyze.patch text/x-diff 11.9 KB

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