* Kevin Grittner: > Dave Crooke <dcrooke@xxxxxxxxx> wrote: > >> create table data >> (id_key int, >> time_stamp timestamp without time zone, >> value double precision); >> >> create unique index data_idx on data (id_key, time_stamp); > >> I need to find the most recent value for each distinct value of >> id_key. > > Well, unless you use timestamp WITH time zone, you might not be able > to do that at all. There are very few places where timestamp > WITHOUT time zone actually makes sense. I don't think PostgreSQL keeps track of actual time zone values, just as it doesn't keep track of the character encoding of TEXT columns. Unless suppressed with WITHOUT TIME ZONE, PostgreSQL makes up some time zone on demand. This makes TIMESTAMP WITH TIME ZONE not that useful, and it's often to use TIMESTAMP WITHOUT TIME ZONE with times in UTC. -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
