"Cade Cairns" <cadec@otii.com> writes:
> test=> select '2007-05-11 09:33:01.167885'::timestamp without time zone,
> ('epoch'::timestamp without time zone + '1178875981.167885
> seconds'::interval)::timestamp without time zone;
> timestamp | timestamp
> ----------------------------+----------------------------
> 2007-05-11 09:33:01.167885 | 2007-05-11 09:33:01.167885
> (1 row)
> test=> select '2007-05-11 09:33:01.167885'::timestamp without time zone =
> ('epoch'::timestamp without time zone + '1178875981.167885
> seconds'::interval)::timestamp without time zone;
> ?column?
> ----------
> f
> (1 row)
If you're using floating-point timestamps (which is the default build)
you are up against the limit of accuracy of a standard float8 value.
IOW that's not really exactly 09:33:01.167885, but close to it.
Checking this example shows that the two float timestamps internally
are 232191181.16788501 and 232191181.16788507.
regards, tom lane