From: | Bruce Momjian <bruce(at)momjian(dot)us> |
---|---|
To: | Kevin Grittner <Kevin(dot)Grittner(at)wicourts(dot)gov> |
Cc: | Robert Haas <robertmhaas(at)gmail(dot)com>, Teodor Sigaev <teodor(at)sigaev(dot)ru>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>, Oleg Bartunov <oleg(at)sai(dot)msu(dot)su> |
Subject: | Re: Re: [GENERAL] contrib/plantuner - enable PostgreSQL planner hints |
Date: | 2009-10-13 14:17:08 |
Message-ID: | 200910131417.n9DEH8715824@momjian.us |
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Lists: | pgsql-general pgsql-hackers |
Kevin Grittner wrote:
> Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
>
> > I sometimes want to know what the planner thinks the cost of some
> > plan other than the one actually selected would be.
>
> Another DBMS I used for years had a way to turn on an *extremely*
> verbose mode for their planner; it showed everything it considered
> with its related cost information. Even a moderately complex query
> generated hundreds or thousands of lines of output, so I rarely used
> it; but for those particularly stubborn queries, where you just can't
> understand why it's picking the plan it is, a little work wading
> through the output would *always* clear up the mystery.
>
> Now that we can generate EXPLAIN output in more structured formats,
> perhaps we could think about adding an "extremely verbose" mode where
> the planner would "think out loud" as a whole separate section from
> where we show the chosen plan?
Well, we have OPTIMIZER_DEBUG, which is a compile-time flag, but that
perhaps can be changed to output as part of EXPLAIN.
--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com
+ If your life is a hard drive, Christ can be your backup. +
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