=?iso-8859-1?Q?Hans=2DJ=FCrgen=20Sch=F6nig?= <hs(at)cybertec(dot)at> writes:
> Surprisingly "-" is defined for (date, date).
What's surprising about that? It yields an integer number of days
between the dates:
regression=# select '2001-06-12'::date - '2000-06-12'::date;
?column?
----------
365
(1 row)
> performance=# SELECT timestamp('2001-06-12'::date - '2000-06-12'::date);
> timestamp
> ------------------------
> 1970-01-01 01:06:05+01
> (1 row)
timestamp(integer) converts a Unix timestamp value (seconds since 1970)
into a timestamp.
regards, tom lane