In current sources (compiled without --enable-integer-datetimes) I get
regression=# select interval(0) '1 day 23:44:55.667677' ;
interval
-----------------------
1 day 23:44:55.667677
(1 row)
I was expecting it to round off ... I think there's something wrong with
the arithmetic in AdjustIntervalForTypmod.
regards, tom lane