Re: CREATE or REPLACE function pg_catalog.*

John Hansen <john@geeknet.com.au> writes:
> When doing CREATE or REPLACE FUNCTION of a builtin function, it seems to
> have no effect if its in the 'C" language. SQL functions seem to work,
> but as neilc pointed out, it may be due to the SQL function being
> inlined.
> The builtin function is still called, not the userdefined function for
> 'C' language functions.

You can't override a builtin C function that way because there is a
built-in map from function OID to builtin function address, and it's
consulted before trying to look in pg_proc.

This behavior is not really open to negotiation; not only on grounds of
speed, but on grounds of circularity.  (The functions used in the
process of looking up entries in pg_proc itself obviously must have such
a short circuit...)  You'd have to build a modified backend in which the
particular functions you want to replace are not listed in the builtin
mapping table.
        regards, tom lane