From: Bryce Nesbitt <bryce2@obviously.com>
To: pgsql-performance@postgresql.org
Cc: Tom Lane <tgl@sss.pgh.pa.us>
Subject: Re: Re: 512,600ms query becomes 7500ms... but why? Postgres 8.3 query planner quirk?
Date: Fri, 12 Feb 2010 23:55:07 -0800
Message-ID: <4B765ADB.5060305@obviously.com> (raw)
In-Reply-To: <28370.1265860369@sss.pgh.pa.us>
References: <4B723042.7090406@obviously.com>
<4B726E81.2060904@obviously.com>
<603c8f071002101231k45e9161eyeacf9072219489eb@mail.gmail.com>
<4B7362DC.2060301@obviously.com>
<28370.1265860369@sss.pgh.pa.us>
Tom Lane wrote:
> Given that it estimated 1 row out of "words" (quite correctly) and 12264
> rows out of each scan on article_words, you'd think that the join size
> estimate would be 12264, which would be off by "only" a factor of 3 from
> the true result. Instead it's 23, off by a factor of 200 :-(.
>
Has anyone every proposed a "learning" query planner? One that
eventually clues in to estimate mismatches like this?
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To: pgsql-performance@postgresql.org
Cc: bryce2@obviously.com, tgl@sss.pgh.pa.us
Subject: Re: Re: 512,600ms query becomes 7500ms... but why? Postgres 8.3 query planner quirk?
In-Reply-To: <4B765ADB.5060305@obviously.com>
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