On Wed, May 9, 2012 at 2:52 PM, Tom Lane <tgl@xxxxxxxxxxxxx> wrote: > Chris Angelico <rosuav@xxxxxxxxx> writes: >> I have a table with a timestamptz column for the "effective date/time" >> of the row, and need to have some queries that look only for those >> entries for which that is in the future or VERY recently - which will >> be a small minority of rows. I'm looking at something like: > >> CREATE INDEX on tablename (effective) where effective>timestamptz >> 'now'-interval '21 days' > > I think this falls under the rubric of "premature optimization is the > root of all evil". Just use a plain index on the timestamptz column > and be happy. Searches that only look at the extremal values of a > column work perfectly well with a full index, because they only need to > examine a small range of the index. The index is actually on two columns, an account ID followed by the effective date - I need to look up whether any particular account has recent entries. Does that make any difference? Thanks for the advice. I don't have enough data yet to be able to measure these things, and it's good to solve problems before they become critical! ChrisA -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
