Re: Why do we let autovacuum give up?

From: Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>
To: Craig Ringer <craig(at)2ndquadrant(dot)com>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Claudio Freire <klaussfreire(at)gmail(dot)com>, Andres Freund <andres(at)2ndquadrant(dot)com>, Mark Kirkwood <mark(dot)kirkwood(at)catalyst(dot)net(dot)nz>, Jeff Janes <jeff(dot)janes(at)gmail(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org>, "Joshua D(dot) Drake" <jd(at)commandprompt(dot)com>
Subject: Re: Why do we let autovacuum give up?
Date: 2014-01-24 03:42:27
Message-ID: 20140124034227.GY10723@eldon.alvh.no-ip.org
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Craig Ringer escribió:
> On 01/24/2014 11:32 AM, Tom Lane wrote:

> > The hard part of this is that shutting down autovacuum during heavy
> > load may be exactly the wrong thing to do.
>
> Yep. In fact, it may be appropriate to limit or stop autovacuum's work
> on some big tables, while pushing its activity even higher for small,
> high churn tables.
>
> If you stop autovacuum on a message-queue system when load gets high,
> you'll get a giant messy bloat explosion.

The design we had was to have table groups, each with their own set of
custom parameters, and they would change depending on schedule. You
could keep the queue tables in one group which would not change
parameters, and only change the rest.

But as I said, it was never fully implemented. (We had a partial patch
from a GSoC project, IIRC.) I don't have the cycles to implement it
now, anyway.

--
Álvaro Herrera http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services

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