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Re: temporary tables, indexes, and query plans

From: Jon Nelson <jnelson+pgsql(at)jamponi(dot)net>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: temporary tables, indexes, and query plans
Date: 2010-10-27 17:59:40
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-performance
On Wed, Oct 27, 2010 at 12:44 PM, Mladen Gogala
<mladen(dot)gogala(at)vmsinfo(dot)com> wrote:
> On 10/27/2010 1:29 PM, Jon Nelson wrote:
> How big is your default statistics target? The default is rather small, it
> doesn't produce very good or usable histograms.

Currently, default_statistics_target is 50.

I note that if I create a indexes earlier in the process (before the
copy) then they are used.
I'm not trying creating them after the first UPDATE (which updates
2.8million of the 10million rows).
The subsequent UPDATE statements update very few (3-4 thousand for 2
of them, less than a few dozen for the others) and the ones that use
the index only update *1* row.

I'll also try setting a higher default_statistics_target and let you know!


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