ANALYZE test_1;
ANALYZE test_2;

-- VACUUM FULL test_1;
-- VACUUM FULL test_2;

SELECT * FROM test_1;
SELECT * FROM test_2;

SELECT * FROM test_1 JOIN test_2 ON (test_1.col_a = test_2.col_a);
SELECT * FROM test_1 JOIN test_2 ON (test_1.col_b = test_2.col_b);
SELECT * FROM test_1 JOIN test_2 ON (test_1.col_a = test_2.col_b);
