On May 24, 2010, at 4:25 AM, Konrad Garus wrote:
> Do shared_buffers duplicate contents of OS page cache? If so, how do I
> know if 25% RAM is the right value for me? Actually it would not seem
> to be true - the less redundancy the better.
You can look into the pg_buffercache contrib module.
> Another question - is there a tool or built-in statistic that tells
> when/how often/how much a table is read from disk? I mean physical
> read, not poll from OS cache to shared_buffers.
Well, the pg_stat_* tables tell you how much logical IO is going on, but postgres has no way of knowing how effective
theOS or disk controller caches are.
