Re: Slower query after psql changed it's execution plan

From: Tom Lane
Subject: Re: Slower query after psql changed it's execution plan
Date: ,
Msg-id: 8646.1237818398@sss.pgh.pa.us
(view: Whole thread, Raw)
In response to: Slower query after psql changed it's execution plan  (Romuald Brunet)
List: pgsql-performance

Romuald Brunet <> writes:
> After some investigation, we found out that the PostgreSQL server
> (8.1) changed the execution plan (I'm assuming because the number of
> rows increased).

The problem seems to be that the estimate for the number of rows fetched
from dc_post changed drastically --- it was in the right ballpark, and
now it's off by a factor of 30.  Why is that?  Maybe you had had a
special statistics target setting, and it got dropped?

> The statistics are at the default value everywhere (10)

Almost certainly not enough.

            regards, tom lane


pgsql-performance by date:

From: Brian Cox
Date:
Subject: Re: multiple threads inserting into the same table
From: Scott Marlowe
Date:
Subject: Re: multiple threads inserting into the same table