Обсуждение: BUG #4767: create operator - negator doesn't work

The following bug has been logged online:

Bug reference:      4767
Logged by:          fduerr
Email address:      fduerr@gmx.de
PostgreSQL version: 8.3.x 8.4.b1
Operating system:   Debian Lenny
Description:        create operator - negator doesn't work
Details:

Hi,
my apologies beforehand in case i'm just too stupid to understand the
documentation...
i understand, that the operator's negator argument specifies the operator
that, when applied with the same operands, yields the inverted result.
So thats what i did:

CREATE OR REPLACE FUNCTION eq_int_bool(INTEGER, BOOLEAN) RETURNS BOOLEAN AS
 'SELECT CAST($1 AS BOOLEAN)=$2;' LANGUAGE SQL IMMUTABLE;
CREATE OPERATOR = (
 LEFTARG=INTEGER,
 RIGHTARG=BOOLEAN,
 PROCEDURE=eq_int_bool,
 COMMUTATOR= = ,
 NEGATOR= <>
);

And thats, what i got:

SELECT 1=false;
 ?column?
----------
 f
(1 row)

SELECT 1<>false;
8.3.x: ERROR: cache lookup failed for function 0
8.4b1: ERROR: operator is only a shell: integer <> boolean

The workaround is, of course, to define an operator with '<>' as commutator
that returns the negated result. Still i wonder: is it me, the documentation
or pg?

On Tuesday 21 April 2009 14:04:01 fduerr wrote:
> CREATE OR REPLACE FUNCTION eq_int_bool(INTEGER, BOOLEAN) RETURNS BOOLEAN AS
>  'SELECT CAST($1 AS BOOLEAN)=$2;' LANGUAGE SQL IMMUTABLE;
> CREATE OPERATOR = (
>  LEFTARG=INTEGER,
>  RIGHTARG=BOOLEAN,
>  PROCEDURE=eq_int_bool,
>  COMMUTATOR= = ,
>  NEGATOR= <>
> );
>
> And thats, what i got:
>
> SELECT 1=false;
>  ?column?
> ----------
>  f
> (1 row)
>
> SELECT 1<>false;
> 8.3.x: ERROR: cache lookup failed for function 0
> 8.4b1: ERROR: operator is only a shell: integer <> boolean
>
> The workaround is, of course, to define an operator with '<>' as commutator
> that returns the negated result. Still i wonder: is it me, the
> documentation or pg?

What you did above is to specify which operator is the negator of =.  But you
still need to create that operator; it is not created automatically.