max uuid

max_uuid.sql

-- Create a table with a UUID column
CREATE TABLE your_table (
    id serial PRIMARY KEY,
    uuid_column uuid
);

-- Insert 400 rows with UUIDs
INSERT INTO your_table (uuid_column)
SELECT gen_random_uuid() FROM generate_series(1, 400);

SELECT max(uuid_column) from your_table;
/*
Same error as for pgslice

ERROR:  function max(uuid) does not exist
LINE 1: SELECT max(uuid_column) from your_table;
               ^
HINT:  No function matches the given name and argument types. You might need to add explicit type casts.
*/

-- https://gist.github.com/devodo/8b39748d65e8185fbd89
CREATE OR REPLACE FUNCTION max (uuid, uuid)
RETURNS uuid AS $$
BEGIN
	IF $1 IS NULL OR $1 < $2 THEN
		RETURN $2;
	END IF;

	RETURN $1;
END;
$$ LANGUAGE plpgsql;


CREATE AGGREGATE max (uuid)
(
    sfunc = max,
    stype = uuid
);

SELECT max(uuid_column) from your_table;
-- No more issue
-- ffbfca39-7664-495a-b6fe-025ea1c7e6b1