Andrew Dunstan <andrew(at)dunslane(dot)net> writes:
> Now running:
> cluster bar using bar_abcde;
> appears to be very sensitive to the shared buffers setting. In an amazon
> very large memory instance (64GB) and PostgreSQL 9.1.4, I observed the
> following timings:
> Shared Buffers Time
> 48Gb 2058ms
> 8Gb 372ms
> 1gb 67ms
DropRelFileNodeBuffers, perhaps? See recent commits to reduce the cost
of that for large shared_buffers, notably
e8d029a30b5a5fb74b848a8697b1dfa3f66d9697 and
ece01aae479227d9836294b287d872c5a6146a11
regards, tom lane