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: Wed, 16 Mar 2016 14:45:46 +0100
Message-ID: <743161cc-771d-6e2b-c43f-4f2bd1fe6d42@2ndquadrant.com> (raw)
In-Reply-To: <20160316.115824.1975980662850012690.t-ishii@sraoss.co.jp>
References: <1457544102.24545.79.camel@2ndquadrant.com>
<CAMkU=1zL_rwWG991YWLARYgBbzN-Ten8j=XjYQSe3fAGMmOX7g@mail.gmail.com>
<1457906378.27231.10.camel@2ndquadrant.com>
<20160316.115824.1975980662850012690.t-ishii@sraoss.co.jp>
List-Unsubscribe: <mailto:majordomo@postgresql.org?body=unsub%20pgsql-hackers>
Hi,
On 03/16/2016 03:58 AM, Tatsuo Ishii wrote:
> I apology if it's already discussed. I am new to this patch.
>
>> Attached is v15 of the patch series, fixing this and also doing quite a
>> few additional improvements:
>>
>> * added some basic examples into the SGML documentation
>>
>> * addressing the objectaddress omissions, as pointed out by Alvaro
>>
>> * support for ALTER STATISTICS ... OWNER TO / RENAME / SET SCHEMA
>>
>> * significant refactoring of MCV and histogram code, particularly
>> serialization, deserialization and building
>>
>> * reworking the functional dependencies to support more complex
>> dependencies, with multiple columns as 'conditions'
>>
>> * the reduction using functional dependencies is also significantly
>> simplified (I decided to get rid of computing the transitive closure
>> for now - it got too complex after the multi-condition dependencies,
>> so I'll leave that for the future
>
> Do you have any other missing parts in this work? I am asking
> because I wonder if you want to push this into 9.6 or rather 9.7.
I think the first few parts of the patch series, namely:
* shared infrastructure (0002)
* functional dependencies (0003)
* MCV lists (0004)
* histograms (0005)
might make it into 9.6. I believe the code for building and storing the
different kinds of stats is reasonably solid. What probably needs more
thorough review are the changes in clauselist_selectivity(), but the
code in these parts is reasonably simple as it only supports using a
single multi-variate statistics per relation.
The part (0006) that allows using multiple statistics (i.e. selects
which of the available stats to use and in what order) is probably the
most complex part of the whole patch, and I myself do have some
questions about some aspects of it. I don't think this part might get
into 9.6 at this point (although it'd be nice if we managed to do that).
I can also imagine moving the ndistinct pieces forward, in front of 0006
if that helps getting it into 9.6. There's a bit more work on making it
more flexible, though, to allow handling subsets columns (currently we
need a perfect match).
regards
--
Tomas Vondra http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
--
Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-hackers
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-hackers@postgresql.org
Cc: tomas.vondra@2ndquadrant.com, ishii@postgresql.org, jeff.janes@gmail.com, alvherre@2ndquadrant.com
Subject: Re: multivariate statistics v14
In-Reply-To: <743161cc-771d-6e2b-c43f-4f2bd1fe6d42@2ndquadrant.com>
* 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