From: "Greg Sabino Mullane" <greg@turnstep.com>
To: pgsql-admin@postgresql.org
Subject: Re: Enhancement request
In-Reply-To: <10684.1196480658@sss.pgh.pa.us>
Date: Wed,  5 Dec 2007 14:10:33 -0000
Message-ID: <09fbbcab762fc5279e45349ce1cbad93@biglumber.com>


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Tom Lane wrote:

> Certainly it isn't a mostly-autovacuum world in 8.2 or earlier releases,
> but that's irrelevant to whether it makes sense to expend effort on a
> feature that would appear (at the earliest) in 8.4.  Autovac in 8.3 is
> very significantly ahead of where it was in 8.2 --- to the point that
> we've turned it on by default --- and I predict that the pressure of
> being on by default will really light the afterburners behind its
> development.  I think it's entirely likely that by the time 8.4 is
> ready, it will be perfectly fair to characterize manual vacuuming
> as a buggy-whip technology, at least for all but the
> three-sigmas-above-normal users.

I think this is being extremely over-optimistic. 8.4 is now the next 
release. Autovacuum still has a long ways to go, and it's still fairly 
useless out of the box for large relations. I also truly cannot imagine 
that 8.4 is going to magically solve the vacuum-later vs. 
performance-now issue.

> And I'd *much* rather see development effort going into making that 
> vision come true, than into adding questionably-useful complexity in 
> the support for manual vacuuming.

It doesn't sound questionable, it sounds like a real-world feature 
request from someone who would immediately benefit from it. Also, 
development is not a zero-sum game - someone writing this patch would 
not necessarily have the skills (or time, or interest) in improving 
auto-vacuum.

I am curious however, as to what the future vision of autovacuum is.
Will it be so efficient that it won't impact all but the busiest tables? 
Will it be able to figure out the best time to vacuum on its own?
Will it stop itself mid-run if the need arises?

- --
Greg Sabino Mullane greg@turnstep.com
End Point Corporation
PGP Key: 0x14964AC8 200712050906
http://biglumber.com/x/web?pk=2529DF6AB8F79407E94445B4BC9B906714964AC8
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