Do you see any performance difference between the following approaches? The assumption is that most of the rows in the query will be requested often enough.
1. SQL function.
CREATE OR REPLACE FUNCTION X(IN a_id uuid, IN b_id uuid)
RETURNS int
STABLE
AS $$
SELECT count(1)
FROM A, B
WHERE a_join_id = b_join_id
AND A.a_id = a_id
AND B.b_id = b_id;
$$ LANGUAGE SQL;
SELECT X(a_id, b_id);
2. View.
CREATE OR REPLACE VIEW X AS
SELECT a_id, b_id, count(1) cnt
FROM A, B
WHERE a_join_id = b_join_id
GROUP BY (a_id, b_id)
SELECT cnt FROM X WHERE X.a_id = a_id and X.B_id = b_id;
Thank you,
Igor