pgsql-bugs@postgresql.org writes:
> jw=# select inc_date (date '2002-10-25', interval '1 day');
> inc_date
> ------------
> 2002-10-26 -> ok
> (1 row)
What you probably want here is the date plus integer operator.
There is no date plus interval operator --- what you are actually
getting is implicit promotion of date to timestamp, then timestamp
plus interval, then coercion back to date. Unfortunately that's
going to create roundoff problems when you cross daylight-savings
boundaries.
regards, tom lane