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LRU and full table scans

From: Mike Mascari <mascarm(at)mascari(dot)com>
To: pgsql-hackers(at)postgresql(dot)org
Subject: LRU and full table scans
Date: 2002-02-27 08:09:45
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-hackers
On general a discussion has been taking place regarding cached query
plans and how MySQL invented them. Of course, this is totally false. I
remembered a nice paragraph in the Oracle docs as to the process by
which Oracle uses shared SQL areas to share the execution plan of
identical statements, flushing the area whenever a dependent object was
modified. In searching for the reference, however, I stumbled an
interesting fact. Unlike normal queries where blocks are added to the
MRU end of an LRU list, full table scans add the blocks to the LRU end
of the LRU list. I was wondering, in the light of the discussion of
using LRU-K, if PostgreSQL does, or if anyone has tried, this technique?

Mike Mascari


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