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From: "Dave Dutcher" <dave@tridecap.com>
To: <gry@ll.mit.edu>,
	<pgsql-performance@postgresql.org>
Subject: Re: simple join uses indexes, very slow
Date: Tue, 28 Mar 2006 10:18:25 -0600
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> -----Original Message-----
> From: pgsql-performance-owner@postgresql.org
[mailto:pgsql-performance-
> owner@postgresql.org] On Behalf Of george young
> Sent: Monday, March 27, 2006 12:48 PM
> To: pgsql-performance@postgresql.org
> Subject: [PERFORM] simple join uses indexes, very slow
> 
[Snip]
> 
> Indexes:
>     "parameters_idx" btree (run, opset_num, step_num, opset,
opset_ver,
> step, step_ver, name, split, wafers)
>     "parameters_opset_idx" btree (opset, step, name)
>     "parameters_step_idx" btree (step, name)
> 


Have you tried creating some different indexes on parameters?  I don't
know if it should matter or not, but I would try some indexes like:

(run, opset_num) //Without all the other columns
(opset_num, run) //Backwards
(opset_num)

I don't really know Postgres internals all that well.  It just seems to
me that parameters_idx has a lot of columns this query is not interested
in.  I'd just be curious to see what happens.