Re: multivariate statistics v11

From: Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>
To: Jeff Janes <jeff(dot)janes(at)gmail(dot)com>
Cc: pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: multivariate statistics v11
Date: 2016-03-09 09:54:09
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thanks for looking at the patch. Sorry for the issues, attached is a
version v13 that should fix them (or most of them).

On Tue, 2016-03-08 at 18:24 -0800, Jeff Janes wrote:
> On Tue, Mar 8, 2016 at 12:13 PM, Tomas Vondra
> <tomas(dot)vondra(at)2ndquadrant(dot)com> wrote:
> > Hi,
> >
> > attached is v11 of the patch - this is mostly a cleanup of v10, removing
> > redundant code, adding missing comments, removing obsolete FIXME/TODOs
> > and so on. Overall this shaves ~20kB from the patch (not a primary
> > objective, though).
> This has some some conflicts with the pathification commit, in the
> regression tests.

Yeah, there was one join plan difference, due to the ndistinct
estimation patch. Meh. Fixed.

> To avoid that, I applied it to the commit before that, 3fc6e2d7f5b652b417fa6^

Rebased to 51c0f63e.

> Having done that, In my hands, it fails its own regression tests.
> Diff attached.

Fixed. This was caused by making names of the statistics unique across
tables, thus the regression tests started to fail when executed through
'make check' (but 'make installcheck' was still fine).

The diff however also includes a segfault, apparently in processing of
functional dependencies somewhere in ANALYZE. Sadly I've been unable to
reproduce any such failure, despite running the tests many times (even
when applied on the same commit). Is there any chance this might be due
to a broken build, or something like that. If not, can you try
reproducing it and investigate a bit (enable core dumps etc.)?

> It breaks contrib postgres_fdw, I'll look into that when I get a
> chance of no one beats me to it.
> postgres_fdw.c: In function 'postgresGetForeignJoinPaths':
> postgres_fdw.c:3623: error: too few arguments to function
> 'clauselist_selectivity'
> postgres_fdw.c:3642: error: too few arguments to function
> 'clauselist_selectivity'

Yeah, apparently there are two new calls to clauselist_selectivity, so I
had to add NIL as list of conditions.


Tomas Vondra
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

Attachment Content-Type Size
0001-teach-pull_-varno-varattno-_walker-about-RestrictInf.patch text/x-patch 1.4 KB
0002-shared-infrastructure-and-functional-dependencies.patch text/x-patch 106.3 KB
0003-clause-reduction-using-functional-dependencies.patch text/x-patch 47.7 KB
0004-multivariate-MCV-lists.patch text/x-patch 112.8 KB
0005-multivariate-histograms.patch text/x-patch 136.5 KB
0006-multi-statistics-estimation.patch text/x-patch 98.3 KB
0007-multivariate-ndistinct-coefficients.patch text/x-patch 28.5 KB
0008-change-how-we-apply-selectivity-to-number-of-groups-.patch text/x-patch 1.4 KB
0009-fixup-of-regression-tests-plans-changes-by-group-by-.patch text/x-patch 5.9 KB

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