Re: multivariate statistics v14

From: Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>
To: Jeff Janes <jeff(dot)janes(at)gmail(dot)com>
Cc: Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: multivariate statistics v14
Date: 2016-03-09 17:21:42
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On Wed, 2016-03-09 at 08:45 -0800, Jeff Janes wrote:
> On Wed, Mar 9, 2016 at 7:02 AM, Tomas Vondra
> <tomas(dot)vondra(at)2ndquadrant(dot)com> wrote:
> > Hi,
> >
> > thanks for the feedback. Attached is v14 of the patch series, fixing
> > most of the points you've raised.
> Hi Tomas,
> Applied to aa09cd242fa7e3a694a31f, I still get the seg faults in make
> check if I configure without --enable-cassert.

Ah, after disabling asserts I can reproduce it too. And the reason why
it fails is quite simple - clauselist_selectivity modifies the original
list of clauses, which then confuses cost_qual_eval.

Can you try if the attached patch fixes the issue? I'll need to rework a
bit more of the code, but let's see if this fixes the issue on your
machine too.

> With --enable-cassert, it passes the regression test.

I wonder how can it work with casserts and fail without them. That's
kinda exactly the opposite to what I'd expect ...


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

Attachment Content-Type Size
mvstats-segfault-fix.patch text/x-patch 642 bytes

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