Re: selects with large offset really slow

From: Stephan Szabo <sszabo(at)megazone23(dot)bigpanda(dot)com>
To: John Smith <john_smith_45678(at)yahoo(dot)com>
Cc: <pgsql-general(at)postgresql(dot)org>
Subject: Re: selects with large offset really slow
Date: 2003-02-08 00:20:53
Message-ID: 20030207161931.S62539-100000@megazone23.bigpanda.com
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On Thu, 6 Feb 2003, John Smith wrote:

>
> There are 90K-100K records in each of two tables. This simple join is
> really slow and the larger the offset, the longer it takes. Anything I
> can do to speed it up (a lot)? I've double-checked and there are
> indexes on everything used for joins and ordering.

>
> ############################
>
> explain analyze select l.id, l.url
> from links l
> inner join stats s
> on l.id = s.link_id
> and s.referrer_id = 1
> order by l.url
> limit 100
> offset 90000;

Hmm, do you have an index on the combination of (url, id)? I don't know
if that'd result in a better plan or not, but it may be able to use that
to help.

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