Re: Open issues for HOT patch

From: "Joshua D(dot) Drake" <jd(at)commandprompt(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Pavan Deolasee <pavan(dot)deolasee(at)gmail(dot)com>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Open issues for HOT patch
Date: 2007-09-18 16:31:03
Message-ID: 46EFFD47.1020204@commandprompt.com
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Tom Lane wrote:
> I wrote:
>> * The patch makes undocumented changes that cause autovacuum's decisions
>> to be driven by total estimated dead space rather than total number of
>> dead tuples. Do we like this?

> If we do this, then it's not clear that having pgstats track dead space
> is worth the trouble at all. It might possibly be of value for testing
> purposes to see how well pruning is doing, but I'm unconvinced that it's
> worth bloating stats messages and files to have this number in a
> production system. An alternative that would serve as well for testing
> would be to teach contrib/pgstattuple to measure dead space.

As a DBA, I can say it doesn't really matter to me *how we track* the
dead space, as long as tracking it is:

1. Clear
2. Simple
3. Available by default (thus pgstattuple needs to push into core)

Sincerely,

Joshua D. Drake

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