CREATE OR REPLACE FUNCTION null_safe_cmp (ANYELEMENT, ANYELEMENT)
RETURNS INTEGER IMMUTABLE
LANGUAGE SQL AS $$
SELECT CASE
WHEN NOT ($1 IS DISTINCT FROM $2) THEN 1
ELSE 0
END;
$$;
Even cooler:
CREATE OR REPLACE FUNCTION null_safe_cmp(anyelement, anyelement)
RETURNS integer AS '
SELECT (NOT ($1 IS DISTINCT FROM $2))::integer
' IMMUTABLE LANGUAGE SQL;
---------------------------(end of broadcast)---------------------------
TIP 9: In versions below 8.0, the planner will ignore your desire to
choose an index scan if your joining column's datatypes do not
match
