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From: Pavan Deolasee <pavan.deolasee@gmail.com>
Date: Sun, 29 May 2011 22:49:00 +0530
Message-ID: <BANLkTi=9RZPv9JOjRdSX6imBeSBGLLrCPA@mail.gmail.com>
Subject: Re: [ADMIN] pg_class reltuples/relpages not updated by
	autovacuum/vacuum
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: =?ISO-8859-1?Q?C=E9dric_Villemain?= <cedric.villemain.debian@gmail.com>,
	Greg Stark <gsstark@mit.edu>, Robert Haas <robertmhaas@gmail.com>,
	Kevin Grittner <Kevin.Grittner@wicourts.gov>,
	Florian Helmberger <fh@25th-floor.com>,
	Alvaro Herrera <alvherre@commandprompt.com>, pgsql-hackers@postgresql.org
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On Sun, May 29, 2011 at 10:35 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Pavan Deolasee <pavan.deolasee@gmail.com> writes:
>> I am sorry if I sounded terse above. But my gripe is that sometimes we
>> are too reluctant to listen to ideas and insist on producing some hard
>> numbers first which might take significant efforts. But we are not
>> equally strict when such changes are introduced initially.
>
> The reason for not wanting to change it without some actual evidence
> is that there is already evidence: the code has been in the field with
> this setting since 8.4, and nobody's vacuum performance has fallen off a
> cliff.

Well, that's probably because there was definitely much improvement
over what existed before. But that does not mean we can't make it
better. IOW there are no complaints because there is no regression.

> So while I'd agree that there was little testing done before the
> code went in, there is more than zero reason to leave it where it is.
> Without some positive evidence showing that another value is better,
> I'm disinclined to change it. =A0I also think that you're not helping
> by complaining about the code without being willing to do some work
> to try to collect such evidence.
>

I am not complaining about the code. I am suggesting we can be more
receptive to ideas, especially when we know what we have today was not
backed by any evidence either. I will anyways do some tests and post
numbers when I work on single-pass vacuum patch. I'll try to
experiment with this stuff at that time.

Thanks,
Pavan

--=20
Pavan Deolasee
EnterpriseDB=A0 =A0=A0 http://www.enterprisedb.com