Re: WIP: Faster Expression Processing v4

From: Andres Freund <andres(at)anarazel(dot)de>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Ants Aasma <ants(dot)aasma(at)eesti(dot)ee>, Heikki Linnakangas <hlinnaka(at)iki(dot)fi>, Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: WIP: Faster Expression Processing v4
Date: 2017-03-27 17:33:40
Message-ID: 20170327173340.nbz5dxltij3axhrw@alap3.anarazel.de
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On 2017-03-27 13:30:11 -0400, Tom Lane wrote:
> Andres Freund <andres(at)anarazel(dot)de> writes:
> > On 2017-03-27 12:18:37 -0400, Tom Lane wrote:
> >> My feeling at this point is that we might be better off disabling
> >> the computed-goto case by default. At the very least, we're going
> >> to need a version check that restricts it to latest gcc.
>
> > In my measurements it's still faster in at least gcc-5/6, even without
> > the option (largely because it avoids array bounds checks on the jump
> > table built for the switch).
>
> Hm. What test cases are you using?

I used tpc-h - seems like a realistic enough testcase.

Andres

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