Horton

Re: [HACKERS] PATCH: multivariate histograms and MCV lists

Tomas Vondra <tomas.vondra@2ndquadrant.com>

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From: Tomas Vondra <tomas.vondra@2ndquadrant.com>
To: David Rowley <david.rowley@2ndquadrant.com>, Alvaro Herrera <alvherre@2ndquadrant.com>
Cc: Michael Paquier <michael@paquier.xyz>, Andres Freund <andres@anarazel.de>, Dean Rasheed <dean.a.rasheed@gmail.com>, Thomas Munro <thomas.munro@enterprisedb.com>, Bruce Momjian <bruce@momjian.us>, Mark Dilger <hornschnorter@gmail.com>, Pg Hackers <pgsql-hackers@postgresql.org>
Date: 2019-02-06T23:44:08Z
Lists: pgsql-hackers 
On 2/6/19 10:59 PM, David Rowley wrote:
> On Thu, 7 Feb 2019 at 03:16, Alvaro Herrera <alvherre@2ndquadrant.com> wrote:
>> I wonder what should we be doing with this series -- concretely, should
>> the effort concentrate on one of the two patches, and leave the other
>> for pg13, to increase the chances of the first one being in pg12?  I
>> would favor that approach, since it's pretty late in the cycle by now
>> and it seems dubious that both will be ready.
> 
> I mostly have been reviewing the MCV patch with the thoughts that one
> is better than none in PG12.  I don't see any particular reason that
> we need both in the one release.
> 

I agree with that, although most of the complexity likely lies in
integrating the stats into the selectivity estimation - if we get that
right for the MCV patch, adding histogram seems comparably simpler.

But yeah, let's focus on the MCV part.

regards

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

Commits

  1. Convert pre-existing stats_ext tests to new style

  2. Add support for multivariate MCV lists

  3. Improve ANALYZE's strategy for finding MCVs.

  4. Clone extended stats in CREATE TABLE (LIKE INCLUDING ALL)

  5. Try again to fix accumulation of parallel worker instrumentation.

  6. Adjust psql \d query to avoid use of @> operator.

  7. Message style fixes

  8. Add security checks to selectivity estimation functions