Re: ARC patent

From: Manfred Koizar <mkoi-pg(at)aon(dot)at>
To: Hannu Krosing <hannu(at)tm(dot)ee>
Cc: Neil Conway <neilc(at)samurai(dot)com>, Simon Riggs <simon(at)2ndquadrant(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, "Joshua D(dot) Drake" <jd(at)commandprompt(dot)com>, Jeff Davis <jdavis-pgsql(at)empires(dot)org>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: ARC patent
Date: 2005-01-21 14:42:38
Message-ID: qo42v01e2jlesq1f7at1h92b47943rfeu8@email.aon.at
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On Fri, 21 Jan 2005 02:31:40 +0200, Hannu Krosing <hannu(at)tm(dot)ee> wrote:
>2) Another simple, but nondeterministic, hack would be using randomness,
>i.e.
>
> 2.1) select a random buffer in LR side half (or 30% or 60%) of
> for replacement.
>
> 2.2) dont last accessed pages to top of LRU list immediately,
> just push them uphill some amount, either random, or
> perhaps 1/2 the way to top at each access.

Sounds good, but how do find the middle of a linked list? Or the other
way round: Given a list element, how do you find out its position in a
linked list? So the only approach that is easily implementable is

2.3) If a sequential scan hint flag is set, put the buffer into the
free list at a random position.

Servus
Manfred

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