On Tue, Dec 10, 2013 at 12:13 AM, Mark Kirkwood <mark.kirkw...@catalyst.net.nz> wrote: > Just one more... > > The Intel 520 with ext4: > > > Without patch: ANALYZE pgbench_accounts 5s > With patch: ANALYZE pgbench_accounts 1s > > And double checking - > With patch, but effective_io_concurrency = 1: ANALYZE pgbench_accounts 5s > > These results look more like Heikki's. Which suggests more benefit on SSD > than spinning disks. Some more data points (apart from mine) would be good > to see tho.
Assuming ANALYZE is sampling less than 5% of the table, I'd say fadvising will always be a win. I'd also suggest higher e_i_c for rotating media. Rotating media has longer latencias, and e_i_c has to be computed in terms of latency, rather than "spindles" when doing prefetch. For backward index scans, I found the optimum number for a single spindle to be about 20. -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
