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Re: 8rc2 & BLCKSZ

From: Mario Weilguni <mweilguni(at)sime(dot)com>
To: pgsql-performance(at)postgresql(dot)org
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Vivek Khera <khera(at)kcilink(dot)com>
Subject: Re: 8rc2 & BLCKSZ
Date: 2004-12-23 07:00:41
Message-ID: 200412230800.41210.mweilguni@sime.com (view raw or flat)
Thread:
Lists: pgsql-performance
Am Mittwoch, 22. Dezember 2004 22:04 schrieb Tom Lane:
> Vivek Khera <khera(at)kcilink(dot)com> writes:
> > One of the suggestions handed to me a long time ago for speeding up PG
> > on FreeBSD was to double the default blocksize in PG.  I tried it, but
> > found not a significant enough speed up to make it worth the trouble
> > to remember to patch every version of Pg during the upgrade path (ie,
> > 7.4.0 -> 7.4.2 etc.)  Forgetting to do that would be disastrous!
>
> Not really --- the postmaster will refuse to start if the BLCKSZ shown
> in pg_control doesn't match what is compiled in.  I concur though that
> there may be no significant performance gain.  For some workloads there
> may well be a performance loss from increasing BLCKSZ.

I've several databases of the same version 7.2 with rowsizes from 8k and 32k 
with the same workload (a content management system), and the performance of 
the 32k variants is slightly better for a few queries, overall responsivness 
seems to better with 8k (maybe because the 8k variant has 4x more buffers).

Regards,
 Mario Weilguni

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