gistfile1.txt

RESET SESSION AUTHORIZATION;
DROP TABLE IF EXISTS s1, s2 CASCADE;
DROP VIEW IF EXISTS v2;
DROP ROLE IF EXISTS user1;

CREATE ROLE user1;
CREATE TABLE s1 (a int, b text);
INSERT INTO s1 (SELECT x, md5(x::text) FROM generate_series(-10,10) x);

CREATE TABLE s2 (x int, y text);
INSERT INTO s2 (SELECT x, md5(x::text) FROM generate_series(-6,6) x);
CREATE VIEW v2 AS SELECT * FROM s2 WHERE y like '%af%';

GRANT SELECT ON s1, s2, v2 TO user1;

CREATE POLICY p1 ON s1 FOR SELECT USING (a in (select x from s2 where y like '%2f%'));
CREATE POLICY p2 ON s2 FOR SELECT USING (x % 2 = 0);

SET SESSION AUTHORIZATION user1;
SELECT * FROM s1;
EXPLAIN (COSTS OFF) SELECT * FROM only s1;

                         QUERY PLAN                          
-------------------------------------------------------------
 Subquery Scan on s1
   Filter: f_leak(s1.b)
   ->  Hash Join
         Hash Cond: (s1_1.a = s2.x)
         ->  Seq Scan on s1 s1_1
         ->  Hash
               ->  HashAggregate
                     Group Key: s2.x
                     ->  Subquery Scan on s2
                           Filter: (s2.y ~~ '%2f%'::text)
                           ->  Subquery Scan on s2_1
                                 Filter: ((s2_1.x % 2) = 0)
                                 ->  Seq Scan on s2 s2_2
                                       Filter: ((x % 2) = 0)