Re: Query slow after analyse on postgresql 8.2

Thanks Tom,

alter table boden.massnahmeobjekt alter column aktennummer set statistics 1000;

fixed it.

Regards
Christian

-----Ursprüngliche Nachricht-----
Von: pgsql-performance-owner(at)postgresql(dot)org [mailto:pgsql-performance-owner(at)postgresql(dot)org] Im Auftrag von Tom Lane
Gesendet: Donnerstag, 17. Juni 2010 16:59
An: Kaufhold, Christian (LFD)
Cc: pgsql-performance(at)postgresql(dot)org
Betreff: Re: [PERFORM] Query slow after analyse on postgresql 8.2

"Kaufhold, Christian (LFD)" <Christian(dot)Kaufhold(at)blfd(dot)bayern(dot)de> writes:
> I have the following query that I run agains postgresql 8.2:
> ...
> But when I run analyse the same query runs for hours.

Seems like the core of the problem is here:

> -> Seq
> Scan on massnahmeobjekt m (cost=0.00..3271.88 rows=1 width=94)
> (actual
> time=0.387..577.771 rows=3694 loops=1)
> Filter: ((aktennummer)::text ~* 'M\\-2009\\-1'::text)

If that rowcount estimate weren't off by three orders of magnitude you probably would be getting a more appropriate plan. The first thing you could try is increasing the statistics target for aktennummer. Also, if you're running in a non-C locale and this is 8.2.5 or older, try a more recent 8.2.x. Updating to 8.3 or 8.4 might help even more.

regards, tom lane

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