Re: pgbench - add pseudo-random permutation function - Mailing list pgsql-hackers

From Fabien COELHO
Subject Re: pgbench - add pseudo-random permutation function
Date
Msg-id alpine.DEB.2.21.1903030947200.8095@lancre
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In response to Re: pgbench - add pseudo-random permutation function  (Fabien COELHO <coelho@cri.ensmp.fr>)
Responses Re: Re: pgbench - add pseudo-random permutation function
List pgsql-hackers
> 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.

-- 
Fabien.
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