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Date: Wed, 11 May 2005 22:59:40 +0200
From: Guillaume Smet <guillaume_ml@smet.org>
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To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: josh@agliodbs.com, pgsql-performance@postgresql.org
Subject: Re: Bad plan after vacuum analyze
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Josh, Tom,

Thanks for your explanations.

> In the meantime it seems like the quickest answer for Guillaume might
> be to try to avoid keeping any NULLs in parent_application_id.

I can't do that as the majority of the applications don't have any 
parent one. Moreover, we use a third party application and we cannot 
modify all its internals.

Anyway, I tried to work on the statistics as you told me and here are 
the results:
ccm_perf=# ALTER TABLE acs_objects ALTER COLUMN object_id SET STATISTICS 30;
ALTER TABLE
ccm_perf=# ANALYZE acs_objects;
ANALYZE

ccm_perf=# \i query_section.sql
... correct plan ...
  Total runtime: 0.555 ms

So I think I will use this solution for the moment.

Thanks a lot for your help.

Regards

--
Guillaume