Re: Bad query optimizer misestimation because of TOAST

From: Markus Schaber <schabios(at)logi-track(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: PostgreSQL Performance List <pgsql-performance(at)postgresql(dot)org>, PostGIS Users Discussion <postgis-users(at)postgis(dot)refractions(dot)net>
Subject: Re: Bad query optimizer misestimation because of TOAST
Date: 2005-02-07 14:07:44
Message-ID: 42077630.5020802@logi-track.com
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Hi, Tom,

Tom Lane schrieb:
> Markus Schaber <schabios(at)logi-track(dot)com> writes:
>> [Query optimizer misestimation using lossy GIST on TOASTed columns]
>
> What I would be inclined to do is to extend ANALYZE to make an estimate
> of the extent of toasting of every toastable column, and then modify
> cost_qual_eval to charge a nonzero cost for evaluation of Vars that are
> potentially toasted.

What to do now? To fix this issue seems to be a rather long-term job.

Is it enough to document workarounds (as in PostGIS), provided that
there are such workarounds for other GIST users?

Is there a bug tracking system we could file the problem, so it does not
get lost?

Markus
--
markus schaber | dipl. informatiker
logi-track ag | rennweg 14-16 | ch 8001 zürich
phone +41-43-888 62 52 | fax +41-43-888 62 53
mailto:schabios(at)logi-track(dot)com | www.logi-track.com

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