Re: Custom Operators Cannot be Found for Composite Type Values

On Mar 7, 2012, at 8:23 PM, Tom Lane wrote:

> You have not told the system that your operator is equality for the
> datatype. It's just a random operator that happens to be named "=".
> We try to avoid depending on operator names as cues to semantics.
>
> You need to incorporate it into a default hash or btree opclass before
> the composite-type logic will accept it as the thing to use for
> comparing that column.

Ah, okay. Just need more stuff, I guess:

CREATE OR REPLACE FUNCTION json_cmp(
json,
json
) RETURNS INTEGER LANGUAGE SQL STRICT IMMUTABLE AS $$
SELECT bttextcmp($1::text, $2::text);
$$;

CREATE OR REPLACE FUNCTION json_eq(
json,
json
) RETURNS BOOLEAN LANGUAGE SQL STRICT IMMUTABLE AS $$
SELECT bttextcmp($1::text, $2::text) = 0;
$$;

CREATE OPERATOR = (
LEFTARG = json,
RIGHTARG = json,
PROCEDURE = json_eq
);

CREATE OPERATOR CLASS json_ops
DEFAULT FOR TYPE JSON USING btree AS
OPERATOR 3 = (json, json),
FUNCTION 1 json_cmp(json, json);

This seems to work.

Best,

David