Re: Constraint exclusion can't process simple constant expressions? - Mailing list pgsql-performance

Josh Berkus <josh@agliodbs.com> writes:
>> timestamptz + interval is not immutable --- in fact, the particular
>> example you give (ts + '1 day') is certainly dependent on timezone
>> setting.

> Why not?  Given that the time zone will be the same for both the
> timestamptz and the interval, how would the result not be immutable?

The reason it depends on the timezone is that the result varies if
"plus one day" means crossing a DST boundary.

            regards, tom lane