Message-ID: <4E860E09.7090107@agliodbs.com>
Date: Fri, 30 Sep 2011 11:44:25 -0700
From: Josh Berkus <josh@agliodbs.com>
Organization: PostgreSQL Experts Inc.
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To: Tom Lane <tgl@sss.pgh.pa.us>
CC: postgres performance list <pgsql-performance@postgresql.org>
Subject: Re: Shortcutting too-large offsets?
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Tom,

> In principle, yeah, we could make it do that, but it seems like a likely
> source of maintenance headaches.  This example is not exactly compelling
> enough to make me want to do it.  Large OFFSETs are always going to be
> problematic from a performance standpoint, and the fact that we could
> short-circuit this one corner case isn't really going to make them much
> more usable.

It's not that uncommon of a corner case though; it's one which happens
all the time in webapps which paginate.  People just have to ask for a
page after the end.  It's really a question of how simple the code to
make the optimization would be; if it would be a 5-line patch, then it's
worth it; if it would be a 110-line refactor, no.

Lemme see if I can figure it out ...

-- 
Josh Berkus
PostgreSQL Experts Inc.
http://pgexperts.com