Re: First set of OSDL Shared Mem scalability results, some

Jan Wieck <janwieck@yahoo.com>

From: Jan Wieck <JanWieck@Yahoo.com>
To: Simon Riggs <simon@2ndquadrant.com>
Cc: josh@agliodbs.com, pgsql-performance@postgresql.org, testperf-general@pgfoundry.org
Date: 2004-10-18T19:17:11Z
Lists: pgsql-hackers, pgsql-performance
On 10/14/2004 6:36 PM, Simon Riggs wrote:

> [...]
> I think Jan has said this also in far fewer words, but I'll leave that to
> Jan to agree/disagree...

I do agree. The total DB size has as little to do with the optimum 
shared buffer cache size as the total available RAM of the machine.

After reading your comments it appears more clear to me. All what those 
tests did show is the amount of high frequently accessed data in this 
database population and workload combination.

> 
> I say this: ARC in 8.0 PostgreSQL allows us to sensibly allocate as large a
> shared_buffers cache as is required by the database workload, and this
> should not be constrained to a small percentage of server RAM.

Right.


Jan

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