Karsten Hilbert <Karsten(dot)Hilbert(at)gmx(dot)net> writes:
>> So I figured it would make sense to add a functional index
>> on date_trunc('day', dob) to the patients table. Which
>> worked (appeared to, at least) with PG 7.4.
For the record, this was changed just before 8.0 release:
http://archives.postgresql.org/pgsql-hackers/2004-10/msg00030.php
regards, tom lane