Subject: Re: multivariate statistics (v19)
To: Alvaro Herrera <alvherre@2ndquadrant.com>
References: <20170130203714.latitwfmrzukgugh@alvherre.pgsql>
Cc: Dilip Kumar <dilipbalaut@gmail.com>,
 Amit Langote <Langote_Amit_f8@lab.ntt.co.jp>,
 Dean Rasheed <dean.a.rasheed@gmail.com>, Heikki Linnakangas
 <hlinnaka@iki.fi>, Michael Paquier <michael.paquier@gmail.com>,
 Robert Haas <robertmhaas@gmail.com>, Tatsuo Ishii <ishii@postgresql.org>,
 David Steele <david@pgmasters.net>, Tom Lane <tgl@sss.pgh.pa.us>,
 Petr Jelinek <petr@2ndquadrant.com>, Jeff Janes <jeff.janes@gmail.com>,
 "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
From: Tomas Vondra <tomas.vondra@2ndquadrant.com>
Message-ID: <c2e06040-3b23-72a3-028c-ec54147b2aab@2ndquadrant.com>
Date: Mon, 30 Jan 2017 22:57:49 +0100
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On 01/30/2017 09:37 PM, Alvaro Herrera wrote:
> Tomas Vondra wrote:
>
>> The 'built' flags may be easily replaced with a check if the bytea-like
>> columns are NULL, and the 'enabled' columns may be replaced by the array of
>> char, just like you proposed.
>>
>> That'd give us a single catalog looking like this:
>>
>> pg_mv_statistics
>>   starelid
>>   staname
>>   stanamespace
>>   staowner      -- all the above as currently
>>   staenabled	array of "char" {d,f,s}
>>   stakeys
>>   stadeps  (dependencies)
>>   standist (ndistinct coefficients)
>>   stamcv   (MCV list)
>>   stahist  (histogram)
>>
>> Which is probably a better / simpler structure than the current one.
>
> Looks good to me.  I don't think we need to keep the names very short --
> I would propose "standistinct", "stahistogram", "stadependencies".
>

Yeah, I got annoyed by the short names too.

This however reminds me that perhaps pg_mv_statistic is not the best 
name. I know others proposed pg_statistic_ext (and pg_stats_ext), and 
while I wasn't a big fan initially, I think it's a better name. People 
generally don't know what 'multivariate' means, while 'extended' is 
better known (e.g. because Oracle uses it for similar stuff).

So I think I'll switch to that name too.

regards

-- 
Tomas Vondra                  http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services


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