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Re: Simple queries take forever to run

From: "Christopher Kings-Lynne" <chriskl(at)familyhealth(dot)com(dot)au>
To: "Michael Guerin" <guerin(at)rentec(dot)com>,<pgsql-performance(at)postgresql(dot)org>
Subject: Re: Simple queries take forever to run
Date: 2003-08-28 01:29:01
Message-ID: 010101c36d03$c2dae240$2800a8c0@mars (view raw or flat)
Thread:
Lists: pgsql-performance
> postgresql version 7.3.3
> .conf params changed from defaults.
> shared_buffers = 64000
> sort_mem = 64000
> fsync = false
> effective_cache_size = 400000
>
> ex. query: select * from x where id in (select id from y);
>
> There's an index on each table for id.  SQL Server takes <1s to return,
> postgresql doesn't return at all, neither does explain analyze.
> x has 1200673 rows
> y has 1282 rows
>
> It seems like its ignoring the index and not using enough memory.. any
> ideas?

This is a known problem in 7.3, it is much faster in 7.4b1.  This should be
very, very fast though, and do exactly the same thing:

select * from x where exists (select id from y where y.id=x.id);

Chris


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