From: | Scott Marlowe <scott(dot)marlowe(at)ihs(dot)com> |
---|---|
To: | Søren Boll Overgaard <postgres(at)fork(dot)dk> |
Cc: | <pgsql-general(at)postgresql(dot)org> |
Subject: | Re: trouble with (lack of) indexing |
Date: | 2002-05-09 21:38:20 |
Message-ID: | Pine.LNX.4.33.0205091537180.5059-100000@css120.ihs.com |
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Thread: | |
Lists: | pgsql-general |
On Thu, 9 May 2002, Søren Boll Overgaard wrote:
> Hello
>
> I am currently involved in a rather large project relying heavily on the use of
> postgresql[1], but we have run into a rather annoying snag.
> We currently have two databases set up. One for testing, and one for production.
> Both run on FreeBSD, and perform very well since the last upgrade.
> However, here is the problem. When executing a certain select statement (shown
> below) on the production database, we get a sequential table scan (of a rather
> large table), which causes the machine on which it runs to max out all possible
> disk I/O. However, when the excact same query is executed on the test
> database, we get an index scan instead of a sequential one. Obviously,
> something differes between the two databases, but we simply cannot track down
> what it is. I would greatly appreciate any input you might be able to offer.
> Here are the queries and their accompanying query plans:
Couple of quick questions...
Have you run vacuum analyze on both databases?
What are your settings in the postgresql.conf for cpu_tuple_cost and such?
You can check them with 'show all' from psql in 7.2.x and later.
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