From: Tomas Vondra <tomas.vondra@2ndquadrant.com>
To: Tatsuo Ishii <ishii@postgresql.org>
Cc: jeff.janes@gmail.com
Cc: alvherre@2ndquadrant.com
Cc: pgsql-hackers@postgresql.org
Subject: Re: multivariate statistics v14
Date: Tue, 22 Mar 2016 14:49:15 +0100
Message-ID: <c109b602-8481-a60b-2daf-11545e79a478@2ndquadrant.com> (raw)
In-Reply-To: <20160322.214615.1524680563827969904.t-ishii@sraoss.co.jp>
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Hi,
On 03/22/2016 01:46 PM, Tatsuo Ishii wrote:
...
> Sorry, maybe I did not explain clearly. My question is, if put
> patches only 0002 to 0005 into 9.6, does it still give any visible
> benefit to users?
The users will be able to define statistics with the limitation that
only a single one (the one covering the most columns referenced by the
clauses) can be used when estimating a query. Which is not perfect, but
I think it's a valuable improvement.
It might also be possible to split 0006 into smaller pieces, for example
implementing the "non-overlapping statistics" case first and then
extending it to more complicated cases. That might increase the change
of getting at least some of that into 9.6 ...
But considering it's not clear whether the initial chunks are likely to
make it into 9.6 - I kinda expect a fair amount of comments from TL
about the preceding parts, who mentioned he might look at the patch this
week. So I'm not sure splitting 0006 into smaller pieces makes sense at
this point.
regards
--
Tomas Vondra http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
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Cc: tomas.vondra@2ndquadrant.com, ishii@postgresql.org, jeff.janes@gmail.com, alvherre@2ndquadrant.com
Subject: Re: multivariate statistics v14
In-Reply-To: <c109b602-8481-a60b-2daf-11545e79a478@2ndquadrant.com>
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