Re: Re: pgbench - add pseudo-random permutation function

From: David Steele <david(at)pgmasters(dot)net>
To: Hironobu SUZUKI <hironobu(at)interdb(dot)jp>
Cc: Fabien COELHO <coelho(at)cri(dot)ensmp(dot)fr>, Andres Freund <andres(at)anarazel(dot)de>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>
Subject: Re: Re: pgbench - add pseudo-random permutation function
Date: 2019-03-21 17:27:49
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Hi Hironobu,

On 3/3/19 12:55 PM, Fabien COELHO wrote:
>> Indeed, the patch needs a rebase & conflit resolution. I'll do it. Later.
> Here is an update:
>  - take advantage of pg_bitutils (although I noted that the "slow"
>    popcount there could be speeded-up and shorten with a bitwise operator
>    implementation that I just removed from pgbench).
>  - add comments about the bijective transformations in the code.
> As already stated, this function makes sense for people who want to test
> performance with pgbench using non uniform rands. If you do not want to
> do that, you will probably find the function pretty useless. I can't
> help it.
> Also, non uniform rands is also a way to test pg lock contention behavior.

You have signed up as a reviewer for this patch. Do you know when
you'll have time to do the review?


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