Horton

Re: multivariate statistics (v19)

Alvaro Herrera <alvherre@2ndquadrant.com>

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From: Alvaro Herrera <alvherre@2ndquadrant.com>
To: Tomas Vondra <tomas.vondra@2ndquadrant.com>
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>
Date: 2017-01-30T20:37:14Z
Lists: pgsql-hackers 
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".

Thanks,

-- 
Álvaro Herrera                https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

Commits

  1. Collect and use multi-column dependency stats

  2. Implement SortSupport for macaddr data type

  3. Implement multivariate n-distinct coefficients

  4. Generate fmgr prototypes automatically