Re: Using 128-bit integers for sum, avg and statistics aggregates

From: Andres Freund <andres(at)2ndquadrant(dot)com>
To: Petr Jelinek <petr(at)2ndquadrant(dot)com>, Andrew Dunstan <andrew(at)dunslane(dot)net>
Cc: Andreas Karlsson <andreas(at)proxel(dot)se>, Michael Paquier <michael(dot)paquier(at)gmail(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Peter Geoghegan <pg(at)heroku(dot)com>, David Rowley <dgrowleyml(at)gmail(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Using 128-bit integers for sum, avg and statistics aggregates
Date: 2015-03-22 21:32:32
Message-ID: 20150322213232.GF3241@awork2.anarazel.de
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On 2015-03-22 22:20:49 +0100, Andres Freund wrote:
> A compiler bug looks like a not unreasonable bet at this point. I've
> asked Andrew to recompile without optimizations... We'll see whether
> that makes a difference. Jacana is the only compiler with gcc 4.8.1 (or
> is it 4.8.0? there's conflicting output). There've been a number of bugs
> fixed that affect loop unrolling and such.

And indeed, a run of jacana with -O0 fixed it. As you can see in
http://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=jacana&dt=2015-03-22%2020%3A41%3A54
, it still fails, but just because of the exp problem.

My guess it's
http://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=jacana&dt=2015-03-22%2020%3A41%3A54

Do we feel the need to find a workaround if this if it's indeed 4.8.0
and 4.8.1 (and some other releases at the same time) that are
problematic? Given that gcc 4.8.2 was released October 16, 2013 I'm
inclined not to.

Greetings,

Andres Freund

--
Andres Freund http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services

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