Re: [WIP] Zipfian distribution in pgbench

From: Alik Khilazhev <a(dot)khilazhev(at)postgrespro(dot)ru>
To: Fabien COELHO <coelho(at)cri(dot)ensmp(dot)fr>
Cc: PostgreSQL Developers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: [WIP] Zipfian distribution in pgbench
Date: 2017-07-17 11:18:46
Message-ID: BBF6F3DB-A70D-480F-975E-C818643D6184@postgrespro.ru
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> On 17 Jul 2017, at 13:51, Fabien COELHO <coelho(at)cri(dot)ensmp(dot)fr> wrote:
>
>
> Is this bias expected from the drawing method, say because it is approximated and the approximation is weak at some points, or is there an issue with its implementation, says some shift which gets smoothed down for higher indexes?
>

I have checked paper where such implementation was proposed and there theta allowed only on range between 0 and 1. It seems like it is not guaranteed that it should work well when theta is more than 1.

I am attaching paper, see page 23.

Attachment Content-Type Size
syntheticdatagen.pdf application/pdf 105.6 KB
unknown_filename text/plain 120 bytes

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