Re: Scrollable cursors and Sort performance

From: "Jim C(dot) Nasby" <jnasby(at)pervasive(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Simon Riggs <simon(at)2ndquadrant(dot)com>, Martijn van Oosterhout <kleptog(at)svana(dot)org>, pgsql-hackers(at)postgresql(dot)org, pgsql-patches(at)postgresql(dot)org
Subject: Re: Scrollable cursors and Sort performance
Date: 2006-02-12 05:22:18
Message-ID: 20060212052218.GY57845@pervasive.com
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On Sat, Feb 11, 2006 at 07:50:22PM -0500, Tom Lane wrote:
> > On Sat, 2006-02-11 at 11:44 -0600, Jim C. Nasby wrote:
> >> But speaking of documentation, it doesn't actually say what the default
> >> is. Care update that, or should I formally submit a patch?
> >>
> >> [1] http://www.postgresql.org/docs/8.1/interactive/sql-declare.html
>
> Actually, if you submit a patch that says either "SCROLL is the default"
> or "NO SCROLL is the default", it will be rejected as incorrect. The
> reason is that the default behavior is different from either of these,
> as is explained in the NOTES section.

Ok, so *that's* where the bit about the query plan being simple enough.
Based on that, ISTM that it should be premissable for us to decide that
a cursor requiring a sort isn't "simple enough" to support SCROLL.

In any case, here's a patch that makes the non-standard behavior easier
for people to find.
--
Jim C. Nasby, Sr. Engineering Consultant jnasby(at)pervasive(dot)com
Pervasive Software http://pervasive.com work: 512-231-6117
vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461

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declare.sgml.patch text/plain 1021 bytes

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