Re: PostgreSQL runs a query much slower than BDE and MySQL

From: Scott Lamb <slamb(at)slamb(dot)org>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: "Peter Hardman" <peter(at)ssbg(dot)zetnet(dot)co(dot)uk>, pgsql-performance(at)postgresql(dot)org
Subject: Re: PostgreSQL runs a query much slower than BDE and MySQL
Date: 2006-08-17 19:20:11
Message-ID: 451A4BAB-97D2-4292-9CF9-CB6DB5B3BCD4@slamb.org
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I have no idea if there's a standard name or what it may be, but for
what it's worth, this sounds similar to the optimizations I wanted
for a different query:

http://archives.postgresql.org/pgsql-performance/2005-11/msg00037.php

1. Recognize that a term constant across the whole sort is
irrelevant. (In my earlier case, a constant number, but here MAX
(xxx), which seems harder.)
2. Put together two sequences already in the appropriate order,
without resorting. (In my case, a union; here a join.)

though I no longer need them for that problem. I'm quite happy with
the client-side solution we came up with.

--
Scott Lamb <http://www.slamb.org/>

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