Re: Yet another "Why won't PostgreSQL use my index?"

From: "Gregory Wood" <gregw(at)com-stock(dot)com>
To: "PostgreSQL-General" <pgsql-general(at)postgresql(dot)org>
Subject: Re: Yet another "Why won't PostgreSQL use my index?"
Date: 2002-06-20 17:13:30
Message-ID: 002501c2187e$58d47620$7889ffcc@comstock.com
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I am assuming that this query is retrieving what you are looking for:

SELECT pg_statistic.* FROM pg_statistic JOIN pg_attribute ON
starelid=attrelid WHERE attname='idx_siteid';

I've attached the results so they don't wrap quite as badly.

Also included is a count for the individual idx_siteid values, if that might
be useful to see how they are distibuted.

Greg

----- Original Message -----
From: "Stephan Szabo" <sszabo(at)megazone23(dot)bigpanda(dot)com>
To: "Gregory Wood" <gregw(at)com-stock(dot)com>
Cc: "PostgreSQL-General" <pgsql-general(at)postgresql(dot)org>
Sent: Thursday, June 20, 2002 12:19 PM
Subject: Re: [GENERAL] Yet another "Why won't PostgreSQL use my index?"

>
> On Thu, 20 Jun 2002, Gregory Wood wrote:
>
> > Trying to use a single column index on a somewhat large table (1.9M
rows),
> > and PostgreSQL really doesn't want to. It estimates the number of rows
at
> > 12749 (actual 354), which is only .6% of the table... well within
reasonable
> > index range I would think. And yes, I've run an analyze on the table.
>
> It might be interesting to figure out why it's over estimating the rows
> so badly. What do the statistics in pg_statistic for that
> relation/attribute look like?
>

Attachment Content-Type Size
pg_statistic_idx_siteid.txt text/plain 9.2 KB

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