Re: LRU and full table scans

On Wed, 2002-02-27 at 13:09, Mike Mascari wrote:
> On general a discussion has been taking place regarding cached query
> plans and how MySQL invented them.

IMHO the discussion was about cached queries not query plans.

> 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.

This seems really elegant solution , much better than not caching at all
and much better than flushing the whole cache by a large table scan

> I was wondering, in the light of the discussion of
> using LRU-K, if PostgreSQL does, or if anyone has tried, this technique?

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Hannu