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Re: First steps with 8.3 and autovacuum launcher

From: Alvaro Herrera <alvherre(at)commandprompt(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Simon Riggs <simon(at)2ndquadrant(dot)com>, "Matthew T(dot) O'Connor" <matthew(at)zeut(dot)net>, Heikki Linnakangas <heikki(at)enterprisedb(dot)com>, Gregory Stark <stark(at)enterprisedb(dot)com>, Stefan Kaltenbrunner <stefan(at)kaltenbrunner(dot)cc>, Guillaume Smet <guillaume(dot)smet(at)gmail(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: First steps with 8.3 and autovacuum launcher
Date: 2007-10-01 22:56:55
Message-ID: 20071001225655.GA9430@alvh.no-ip.org (view raw or flat)
Thread:
Lists: pgsql-hackers
Tom Lane escribió:
> Simon Riggs <simon(at)2ndquadrant(dot)com> writes:
> > We should not allow VACUUM to be concurrent with either CREATE INDEX or
> > ANALYZE, but then thats not the problem here anyway.
> 
> I can't believe anyone is short-sighted enough to think that.
> 
> The problem here is that autovac takes locks that block foreground
> sessions that want exclusive locks.  We've always known this and always
> ignored it, but if autovac is on by default then it's going to be in
> people's faces a lot more than it was before, and they won't be happy.
> 
> If you insist on crafting a solution that only fixes this problem for
> pg_restore's narrow usage, you'll be back revisiting it before beta1
> has been out a month.

So you say we should make any job that needs an exclusive lock on a
table to be able to cancel a running autovac job?  If we did that,
autovac couldn't do very much of anything.

If that's not what you're saying, I'm afraid I'm not getting it.

-- 
Alvaro Herrera                  http://www.amazon.com/gp/registry/5ZYLFMCVHXC
Maybe there's lots of data loss but the records of data loss are also lost.
(Lincoln Yeoh)

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