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From: Ildar Musin <i.musin@postgrespro.ru>
To: Fabien COELHO <coelho@cri.ensmp.fr>
Cc: pgsql-hackers <pgsql-hackers@postgresql.org>
Subject: Re: General purpose hashing func in pgbench
Date: Mon, 25 Dec 2017 17:55:39 +0300
Message-ID: <af1ccd41-dcd0-f56b-0a05-a558da54762b@postgrespro.ru> (raw)
In-Reply-To: <alpine.DEB.2.20.1712251506160.22976@lancre>
References: <0e8bd39e-dfcd-2879-f88f-272799ad7ef2@postgrespro.ru>
	<alpine.DEB.2.20.1712200807550.5165@lancre>
	<699225ee-c30c-b22e-4028-415e9eab26b2@postgrespro.ru>
	<alpine.DEB.2.20.1712211620040.32625@lancre>
	<80e9c570-5c49-1a01-f309-3d8d0cbbae42@postgrespro.ru>
	<alpine.DEB.2.20.1712240846440.22976@lancre>
	<38f1503e-7b63-4612-24a9-041af25bb022@postgrespro.ru>
	<alpine.DEB.2.20.1712251506160.22976@lancre>


25/12/2017 17:12, Fabien COELHO пишет:
>
> However, the key can be used if controlled so that different values do
> not have the same randomization in different part of the script, so as
> to avoid using the same patterns for different things if not desirable.
Original murmur algorithm accepts seed as a parameter, which can be used
for this purpose. I used value itself as a seed in the patch, but I can
turn it into a function argument.
>
> For the pgbench pseudo-random permutation I'm looking at, the key can
> be specified to control whether the same pattern or not should be used.
>
Just curious, which algorithm are you intended to choose?

-- 
Ildar Musin
Postgres Professional: http://www.postgrespro.com
Russian Postgres Company 





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