Re: Sequential vs. random values - number of pages in B-tree

From: "Daniel Verite" <daniel(at)manitou-mail(dot)org>
To: "Francisco Olarte" <folarte(at)peoplecall(dot)com>
Cc: "pinker" <pinker(at)onet(dot)eu>,"pgsql-general(at)postgresql(dot)org" <pgsql-general(at)postgresql(dot)org>
Subject: Re: Sequential vs. random values - number of pages in B-tree
Date: 2016-08-18 15:24:37
Message-ID: e95bf02e-cd18-4a2b-8e78-80d3fd61b826@mm
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Francisco Olarte wrote:

> unless you know of an easy way to generate a random permutation on the
> fly without using a lot of memory, I do not.

It could be done by encrypting the stream.

For 32 bits integers:
https://wiki.postgresql.org/wiki/Skip32

For 64 bits integers:
https://wiki.postgresql.org/wiki/XTEA

Best regards,
--
Daniel Vérité
PostgreSQL-powered mailer: http://www.manitou-mail.org
Twitter: @DanielVerite

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