On Mon, Mar 7, 2016 at 8:37 AM, Geoff Winkless <pgsqladmin@xxxxxxxx> wrote: > > But as far as I can see, apart from the absolute extremes, the > index-only scan is _always_ going to be quicker than the index+table > scan. If relallvisible is zero, it thinks it gets zero benefit from an index only scan. It thinks that using a larger index has a small, but non-zero, cost over the smaller index. > We can see that by the massive speedup I get by > using index(scid,scdate), which in all other respects is going to > suffer from exactly the same problem from that the scid-only index > suffers. What massive speedup? (scid,scdate) is the index it *does* use in your worse demonstrated case. -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
