The following bug has been logged on the website:
Bug reference: 6401
Logged by: Kenaniah Cerny
Email address: kenaniah(at)gmail(dot)com
PostgreSQL version: 9.1.2
Operating system: Centos 6 x86_64
Description:
----
SELECT point(2, 3) IS DISTINCT FROM point(2, 3);
----
ERROR: operator does not exist: point = point
LINE 1: SELECT point(2, 3) IS DISTINCT FROM point(2, 3)
^
HINT: No operator matches the given name and argument type(s). You might
need to add explicit type casts.
----
According to the docs
(http://www.postgresql.org/docs/current/static/functions-geometry.html#FUNCTIONS-GEOMETRY),
the "same as" operator is the ~= operator, not the = operator.
This problem cascades to the comparison of complex types, such as "OLD IS
DISTINCT FROM NEW" in the context of plpgsql.