Re: shared_buffers performance

"Tom Lane" <tgl@[EMAIL PROTECTED]
> writes:

> Gregory Stark <stark@[EMAIL PROTECTED]
> writes:
>> The transition domain where performance drops dramatically as the
database
>> starts to not fit in shared buffers but does still fit in filesystem
cache.
>
> It looks to me like the knee comes where the DB no longer fits in
> filesystem cache.  

That does seem to make a lot more sense. I think I misread the units of
the
size of the accounts table. Reading it again it seems to be in the 1.5G-2G
range for the transition which with indexes and other tables might be
starting
to stress the filesystem cache -- though it still seems a little low.

I think if I squint I can see another dropoff at the very small scaling
numbers. That must be the point where the database is comparable to the
shared
buffers size. Except then I would expect the green and blue curves to be
pushed to the right a bit rather than just havin a shallower slope.

-- 
  Gregory Stark
  EnterpriseDB          http://www.enterprisedb.com
  Ask me about EnterpriseDB's On-Demand Production Tuning

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