Martijn van Oosterhout <kleptog@svana.org> writes:
> There have been tests that demonstrate that you can raise the buffers
> to a certain point which is optimal and after that it just doesn't
> help [1]. They peg optimal size at 5-10% of memory.
> [1] http://archives.postgresql.org/pgsql-performance/2004-10/msg00110.php
Note however that it's reasonable to think that 8.1 may do better than
8.0 did at performing well with large values of shared_buffers,
primarily because we got rid of the StrategyDirtyBufferList overhead:
http://archives.postgresql.org/pgsql-performance/2004-10/msg00112.php
It'd be interesting to repeat the above-mentioned tests with 8.1.
regards, tom lane