Re: DB cache size strategies - Mailing list pgsql-general

From Tom Lane
Subject Re: DB cache size strategies
Date
Msg-id 15799.1076480224@sss.pgh.pa.us
Whole thread Raw
In response to Re: DB cache size strategies  ("Ed L." <pgsql@bluepolka.net>)
Responses Re: DB cache size strategies  ("Ed L." <pgsql@bluepolka.net>)
List pgsql-general
"Ed L." <pgsql@bluepolka.net> writes:
> So, pursuing theory (1) in 'the time before ARC', assuming you have a
> dedicated box with little or no non-db competition for resources, why give
> PG anymore than is absolutely required (max_connections*2 or 16)?  Why not
> just let the kernel reign as completely as possible?  Is that what you mean
> by "relatively small"?

Well, if you go *really* small then you find a lot of CPU time gets
wasted shuffling data from kernel cache to PG cache.  The sweet spot
for theory (1) seems to be to set shared_buffers in the range of 1000 to
10000 buffers.  (Time was that that was a serious amount of RAM, but
not any more...)

            regards, tom lane

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