| From: | Alvaro Herrera <alvherre(at)2ndquadrant(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Fabien COELHO <coelho(at)cri(dot)ensmp(dot)fr>, Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>, Georgios Kokolatos <gkokolatos(at)pm(dot)me>, PostgreSQL Developers <pgsql-hackers(at)lists(dot)postgresql(dot)org> |
| Subject: | Re: CPU costs of random_zipfian in pgbench |
| Date: | 2019-04-01 21:51:35 |
| Message-ID: | 20190401215135.GA31141@alvherre.pgsql |
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| Lists: | pgsql-hackers |
On 2019-Apr-01, Tom Lane wrote:
> Fabien COELHO <coelho(at)cri(dot)ensmp(dot)fr> writes:
> >> I was wondering about that too. It seems like it'd be a wise idea to
> >> further constrain s and/or n to ensure that the s > 1 code path doesn't do
> >> anything too awful ...
>
> > Yep. The attached version enforces s >= 1.001, which avoids the worse cost
> > of iterating, according to my small tests.
>
> Seems reasonable. Pushed with minor documentation editing.
Ah, so we now we can get rid of the TState * being passed around
separately for expression execution, too?
--
Álvaro Herrera https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
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