|From:||Fabien COELHO <coelho(at)cri(dot)ensmp(dot)fr>|
|To:||Hironobu SUZUKI <hironobu(at)interdb(dot)jp>|
|Cc:||PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>, David Steele <david(at)pgmasters(dot)net>|
|Subject:||Re: pgbench - add pseudo-random permutation function|
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Here is a v15 which is a rebase, plus a large simplification of the modmul
function if an int128 type is available, which is probably always…
Could you have a look and possibly revalidate?
> Sorry for the late reply. I reviewed this patch.
> Function nbits(), which was previously discussed, has been simplified by
> using the function pg_popcount64().
> By adding the mathematical explanation, it has been easier to understand the
> operation of this function.
> I believe that these improvements will have a positive impact on maintenance.
> The patch could be applied successfully and the tests passed without
> So, I think the latest patch is fine.
> Best regards,
>> 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?
Fabien Coelho - CRI, MINES ParisTech
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