On Mon, Dec 8, 2014 at 03:40:43PM -0600, Merlin Moncure wrote: > >> Did not see consistent measurable gains > 256 > >> effective_io_concurrency. Interesting that at setting of '2' (the > >> lowest possible setting with the feature actually working) is > >> pessimal. > > > > Very interesting. When we added a per-tablespace random_page_cost, > > there was a suggestion that we might want to add per-tablespace > > effective_io_concurrency someday: > > What I'd really like to see is to have effective_io_concurrency work > on other types of scans. It's clearly a barn burner on fast storage > and perhaps the default should be something other than '1'. Spinning > storage is clearly dead and ssd seem to really benefit from the posix > readhead api. Well, the real question is knowing which blocks to request before actually needing them. With a bitmap scan, that is easy --- I am unclear how to do it for other scans. We already have kernel read-ahead for sequential scans, and any index scan that hits multiple rows will probably already be using a bitmap heap scan. -- Bruce Momjian <bruce@xxxxxxxxxx> http://momjian.us EnterpriseDB http://enterprisedb.com + Everyone has their own god. + -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
