Hi All I've got a table with (amongst others) two fields: last_updated timestamp with time zone; update_cycle interval; I'd like to create an index on these, to index time "next update" time (last_updated + update_cycle). When I try this I get an error though: main=> create index foo_next_update on foo( (last_updated + update_cycle) ) ; ERROR: functions in index expression must be marked IMMUTABLE Does anyone know why adding two fields like this results in anything other than an immutable function? Under what circumstances could it return a different result? Thanks very much for any help. -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
