Horton

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

Bruce Momjian <bruce@momjian.us>

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From: Bruce Momjian <bruce@momjian.us>
To: Tomas Vondra <tomas.vondra@2ndquadrant.com>
Cc: Dean Rasheed <dean.a.rasheed@gmail.com>, Alvaro Herrera <alvherre@2ndquadrant.com>, Andres Freund <andres@anarazel.de>, Thomas Munro <thomas.munro@enterprisedb.com>, Mark Dilger <hornschnorter@gmail.com>, Adrien Nayrat <adrien.nayrat@dalibo.com>, Pg Hackers <pgsql-hackers@postgresql.org>
Date: 2018-04-07T14:12:01Z
Lists: pgsql-hackers 
On Sun, Apr  1, 2018 at 06:07:55PM +0200, Tomas Vondra wrote:
> Hi,
> 
> The attached patch version modifies how the non-MCV selectivity is
> computed, along the lines explained in the previous message.
> 
> The comments in statext_clauselist_selectivity() explain it in far more
> detail, but we this:

Uh, where are we on this patch?  It isn't going to make it into PG 11? 
Feature development for this has been going on for years.  I thought
when Dean Rasheed got involved that it would be applied for this
release.

I realize this is a complex feature, but I think it will solve 80-90% of
optimizer complaints, and I don't see any other way to fix them than
this.  This seems like the right way to fix optimizer problems, instead
of optimizer hints.

-- 
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

+ As you are, so once was I.  As I am, so you will be. +
+                      Ancient Roman grave inscription +

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