Horton

Re: multivariate statistics (v19)

Michael Paquier <michael.paquier@gmail.com>

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From: Michael Paquier <michael.paquier@gmail.com>
To: Heikki Linnakangas <hlinnaka@iki.fi>
Cc: Tomas Vondra <tomas.vondra@2ndquadrant.com>, Dean Rasheed <dean.a.rasheed@gmail.com>, Robert Haas <robertmhaas@gmail.com>, Tatsuo Ishii <ishii@postgresql.org>, David Steele <david@pgmasters.net>, Tom Lane <tgl@sss.pgh.pa.us>, Álvaro Herrera <alvherre@2ndquadrant.com>, Petr Jelinek <petr@2ndquadrant.com>, Jeff Janes <jeff.janes@gmail.com>, "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Date: 2016-10-04T03:25:08Z
Lists: pgsql-hackers 
On Mon, Oct 3, 2016 at 8:25 PM, Heikki Linnakangas <hlinnaka@iki.fi> wrote:
> Yeah. The idea was to use something like pg_node_tree to store all the
> different kinds of statistics, the histogram, the MCV, and the functional
> dependencies, in one datum. Or JSON, maybe. It sounds better than an opaque
> bytea blob, although I'd prefer something more relational. For the
> functional dependencies, I think we could get away with a simple float
> array, so let's do that in the first cut, and revisit this for the MCV and
> histogram later.

OK. A second thing was related to the use of schemas in the new system
catalogs. As mentioned in [1], those could be removed.
[1]: https://www.postgresql.org/message-id/CAB7nPqTU40Q5_NSgHVoMJfbyH1HDtqMbFDJ+kwFJSpam35b3Qg@mail.gmail.com.

> Separate columns for the functional dependencies, the MCVs,
> and the histogram, probably makes sense anyway.

Probably..
-- 
Michael

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