On Mon, Nov 26, 2012 at 3:29 PM, Jeff Davis <pgsql@j-davis.com> wrote:
> Your intuition here is better than mine, but I am still missing
> something here. If we keep the buffer pinned, then there will be very
> few pin/unpin cycles here, so I don't see where the contention would
> come from (any more than there is contention pinning the root of an
> index).
Based on previous measurements, I think there *is* contention pinning
the root of an index. Currently, I believe it's largely overwhelmed
by contention from other sources, such as the buffer manager lwlocks
and the very-evil ProcArrayLock. However, I believe that as we fix
those problems, this will start to percolate up towards the top of the
heap.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company