Hubert Palme <palme@uni-wuppertal.de> writes:
> adressen=> CREATE INDEX xxx ON geburtstage (geb_monat(geburtstag));
> ERROR: DefineIndex: (null) class not found
> adressen=>
Apparently you're using 6.5 or older ... I'd recommend updating!
IIRC, in <= 6.5 you *must* specify an operator class for a functional
index. So,
CREATE INDEX xxx ON geburtstage (geb_monat(geburtstag) float8_ops);
(assuming that geb_monat returns a float8, else adjust to suit).
Don't have a 6.5 server running anymore to check this on, however.
regards, tom lane