From: Tom Lane <tgl@sss.pgh.pa.us>
To: Gregory Stark <stark@enterprisedb.com>
Cc: Jeff Davis <pgsql@j-davis.com>
Cc: len@pdx.edu
Cc: len@cs.pdx.edu
Cc: pgsql-performance@postgresql.org
Subject: Re: Understanding histograms
Date: Thu, 01 May 2008 00:41:07 -0400
Message-ID: <561.1209616867@sss.pgh.pa.us> (raw)
In-Reply-To: <87skx24zfr.fsf@oxford.xeocode.com>
References: <4817FC00.50609@cs.pdx.edu>
<14251.1209532791@sss.pgh.pa.us>
<c5ee9b8a0804292332q32b468e3ga6b99e25b56c18c7@mail.gmail.com>
<18628.1209566591@sss.pgh.pa.us>
<1209595622.14025.112.camel@dogma.ljc.laika.com>
<26230.1209597464@sss.pgh.pa.us>
<87skx24zfr.fsf@oxford.xeocode.com>
Gregory Stark <stark@enterprisedb.com> writes:
> This is something that needs some serious thought though. In the case of
> partitioned tables I've seen someone get badly messed up plans because they
> had a couple hundred partitions each of which estimated to return 1 row. In
> fact of course they all returned 0 rows except the correct partition. (This
> was in a join so no constraint exclusion)
Yeah, one of the things we need to have a "serious" partitioning
solution is to get the planner's estimation code to understand
what's happening there.
regards, tom lane
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, stark@enterprisedb.com, pgsql@j-davis.com, len@pdx.edu, len@cs.pdx.edu
Subject: Re: Understanding histograms
In-Reply-To: <561.1209616867@sss.pgh.pa.us>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox