Michael van Rooyen wrote:
I have no idea regarding the inner working of the pg's shared cache, but what I would like to find out is whether it is table-row-based, or disk-block-based.
It's block based.
In the case of it being disk-block based, my inclination would be to let the kernel do the buffering. In the case of the cache being table-row-based, I would expect it to be much more space-efficient and I would be inclined to give the memory to the pg. In that case, is it feasible to set shared_buffers to something like 500000 x 8k blocks? We make extensive use of indexes on the larger tables and would seldom, if ever, do sequential scans.
A common rule of thumb people quote here is to set shared_buffers to 1/4 of available RAM, and leave the rest for OS cache. That's probably a good configuration to start with.
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