Re: Bug: Buffer cache is not scan resistant - Mailing list pgsql-hackers

From Luke Lonergan
Subject Re: Bug: Buffer cache is not scan resistant
Date
Msg-id C3E62232E3BCF24CBA20D72BFDCB6BF802CFC0C6@MI8NYCMAIL08.Mi8.com
Whole thread Raw
In response to Re: Bug: Buffer cache is not scan resistant  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses Re: Bug: Buffer cache is not scan resistant  (Heikki Linnakangas <heikki@enterprisedb.com>)
Re: Bug: Buffer cache is not scan resistant  (Hannu Krosing <hannu@skype.net>)
Re: Bug: Buffer cache is not scan resistant  (Tom Lane <tgl@sss.pgh.pa.us>)
Re: Bug: Buffer cache is not scan resistant  (Jeff Davis <pgsql@j-davis.com>)
List pgsql-hackers
Hi Tom,

> Even granting that your conclusions are accurate, we are not
> in the business of optimizing Postgres for a single CPU architecture.

I think you're missing my/our point:

The Postgres shared buffer cache algorithm appears to have a bug.  When
there is a sequential scan the blocks are filling the entire shared
buffer cache.  This should be "fixed".

My proposal for a fix: ensure that when relations larger (much larger?)
than buffer cache are scanned, they are mapped to a single page in the
shared buffer cache.

- Luke



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