From:
PostgreSQL - Hans-Jürgen Schönig <postgres(at)cybertec(dot)at>
To:
Robert Haas <robertmhaas(at)gmail(dot)com>
Cc:
Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>,
pgsql-hackers Hackers <pgsql-hackers(at)postgresql(dot)org>,
Boszormenyi Zoltan <zb(at)cybertec(dot)at>
Subject:
Re: WIP: cross column correlation ...
Date:
2011-02-23 14:54:11
Message-ID:
1CFB88AD-B7E4-4CED-A048-2292E5888B05@cybertec.at (view raw or flat )
Thread:
2011-02-22 19:48:47 from PostgreSQL - Hans-Jürgen Schönig <postgres(at)cybertec(dot)at>
2011-02-23 01:58:00 from Robert Haas <robertmhaas(at)gmail(dot)com>
2011-02-23 02:43:59 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2011-02-23 02:56:37 from Robert Haas <robertmhaas(at)gmail(dot)com>
2011-02-23 03:04:12 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2011-02-23 08:15:39 from PostgreSQL - Hans-Jürgen Schönig <postgres(at)cybertec(dot)at>
2011-02-23 14:48:13 from Robert Haas <robertmhaas(at)gmail(dot)com>
2011-02-23 14:54:11 from PostgreSQL - Hans-Jürgen Schönig <postgres(at)cybertec(dot)at>
2011-02-23 22:37:39 from Bruce Momjian <bruce(at)momjian(dot)us>
2011-02-23 05:50:50 from Nathan Boley <npboley(at)gmail(dot)com>
2011-02-23 14:46:34 from Robert Haas <robertmhaas(at)gmail(dot)com>
2011-02-23 14:56:59 from PostgreSQL - Hans-Jürgen Schönig <postgres(at)cybertec(dot)at>
2011-02-23 08:02:28 from PostgreSQL - Hans-Jürgen Schönig <postgres(at)cybertec(dot)at>
2011-02-23 15:10:07 from Robert Haas <robertmhaas(at)gmail(dot)com>
2011-02-23 22:40:00 from Bruce Momjian <bruce(at)momjian(dot)us>
2011-02-24 20:42:39 from Josh Berkus <josh(at)agliodbs(dot)com>
2011-02-25 06:33:59 from Bruce Momjian <bruce(at)momjian(dot)us>
2011-02-25 13:18:40 from Robert Haas <robertmhaas(at)gmail(dot)com>
2011-02-25 16:45:43 from Cédric Villemain <cedric(dot)villemain(dot)debian(at)gmail(dot)com>
2011-02-25 17:50:51 from Robert Haas <robertmhaas(at)gmail(dot)com>
2011-02-25 22:35:45 from Cédric Villemain <cedric(dot)villemain(dot)debian(at)gmail(dot)com>
2011-02-25 17:03:58 from Rod Taylor <rod(dot)taylor(at)gmail(dot)com>
2011-02-25 19:26:10 from Alvaro Herrera <alvherre(at)commandprompt(dot)com>
2011-02-26 05:24:26 from Robert Haas <robertmhaas(at)gmail(dot)com>
2011-02-28 18:44:08 from Alvaro Herrera <alvherre(at)commandprompt(dot)com>
2011-03-01 00:18:43 from Rod Taylor <rod(dot)taylor(at)gmail(dot)com>
2011-02-26 13:38:31 from Rod Taylor <rod(dot)taylor(at)gmail(dot)com>
2011-02-27 07:59:44 from Bruce Momjian <bruce(at)momjian(dot)us>
2011-02-25 23:41:09 from Josh Berkus <josh(at)agliodbs(dot)com>
2011-02-26 05:29:14 from Robert Haas <robertmhaas(at)gmail(dot)com>
2011-02-26 06:57:54 from Bruce Momjian <bruce(at)momjian(dot)us>
2011-02-26 14:46:55 from Robert Haas <robertmhaas(at)gmail(dot)com>
2011-02-27 08:03:10 from Bruce Momjian <bruce(at)momjian(dot)us>
2011-02-27 17:44:35 from Robert Haas <robertmhaas(at)gmail(dot)com>
2011-02-27 22:17:49 from Josh Berkus <josh(at)agliodbs(dot)com>
2011-02-28 15:13:39 from Robert Haas <robertmhaas(at)gmail(dot)com>
2011-02-28 18:04:54 from Josh Berkus <josh(at)agliodbs(dot)com>
2011-02-28 18:19:46 from Martijn van Oosterhout <kleptog(at)svana(dot)org>
2011-02-28 18:24:13 from Robert Haas <robertmhaas(at)gmail(dot)com>
2011-02-28 18:31:29 from Josh Berkus <josh(at)agliodbs(dot)com>
2011-02-28 18:50:03 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2011-02-28 18:54:23 from Robert Haas <robertmhaas(at)gmail(dot)com>
2011-02-28 19:31:53 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2011-02-28 19:37:23 from Michael Glaesemann <grzm(at)seespotcode(dot)net>
2011-02-28 19:39:19 from Josh Berkus <josh(at)agliodbs(dot)com>
2011-02-28 19:47:23 from "Joshua D(dot) Drake" <jd(at)commandprompt(dot)com>
2011-02-28 20:02:30 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2011-03-02 12:29:59 from Bernd Helmle <mailings(at)oopsware(dot)de>
2011-02-28 20:24:41 from Robert Haas <robertmhaas(at)gmail(dot)com>
2011-03-01 08:50:25 from Dimitri Fontaine <dimitri(at)2ndQuadrant(dot)fr>
2011-02-28 19:47:22 from Euler Taveira de Oliveira <euler(at)timbira(dot)com>
2011-02-28 20:03:33 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2011-02-28 21:13:47 from Greg Stark <gsstark(at)mit(dot)edu>
2011-02-28 22:05:08 from Josh Berkus <josh(at)agliodbs(dot)com>
2011-02-28 22:52:00 from Chris Browne <cbbrowne(at)acm(dot)org>
2011-02-28 22:35:28 from Robert Treat <rob(at)xzilla(dot)net>
2011-02-26 09:33:14 from Grzegorz Jaskiewicz <gj(at)pointblue(dot)com(dot)pl>
2011-02-26 14:45:24 from Robert Haas <robertmhaas(at)gmail(dot)com>
2011-02-26 18:12:42 from PostgreSQL - Hans-Jürgen Schönig <postgres(at)cybertec(dot)at>
2011-02-26 18:44:52 from Greg Stark <gsstark(at)mit(dot)edu>
2011-02-26 18:58:20 from Martijn van Oosterhout <kleptog(at)svana(dot)org>
2011-02-26 20:10:46 from Grzegorz Jaskiewicz <gj(at)pointblue(dot)com(dot)pl>
2011-02-27 08:01:18 from Bruce Momjian <bruce(at)momjian(dot)us>
2011-02-27 17:24:43 from Robert Haas <robertmhaas(at)gmail(dot)com>
2011-02-24 01:09:10 from Josh Berkus <josh(at)agliodbs(dot)com>
2011-02-24 03:11:11 from Robert Haas <robertmhaas(at)gmail(dot)com>
2011-02-24 03:30:08 from Bruce Momjian <bruce(at)momjian(dot)us>
2011-02-24 03:58:08 from Robert Haas <robertmhaas(at)gmail(dot)com>
2011-02-24 15:07:35 from Bruce Momjian <bruce(at)momjian(dot)us>
2011-02-24 06:13:36 from PostgreSQL - Hans-Jürgen Schönig <postgres(at)cybertec(dot)at>
Lists:
pgsql-hackers
>>>
>>
>> cheapest and easiest solution if you run into this: add "fake" functions which the planner cannot estimate properly.
>> use OR to artificially prop up estimates or use AND to artificially lower them. there is actually no need to redesign the schema to get around it but it is such an ugly solution that it does not even deserve to be called "ugly" ...
>> however, fast and reliable way to get around it.
>
> We couldn't possibly design a hint mechanism that would be uglier or
> less future-proof than this workaround (which, by the way, I'll keep
> in mind for the next time I get bitten by this).
>
> --
> Robert Haas
> EnterpriseDB: http://www.enterprisedb.com
> The Enterprise PostgreSQL Company
>
i think the main issue is: what we do is ugly because of despair and a lack of alternative ... what you proposed is ugly by design ;).
overall: the workaround will win the ugliness contest, however ;).
many thanks,
hans
--
Cybertec Schönig & Schönig GmbH
Gröhrmühlgasse 26
A-2700 Wiener Neustadt, Austria
Web: http://www.postgresql-support.de
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