| -- Shape: two independent projected IN subqueries in one SELECT list. Each one | |
| -- is decorrelated on its own, so this measures whether the cost of the first | |
| -- one simply doubles. | |
| SELECT | |
| count(*) FILTER (WHERE a) AS a_count, | |
| count(*) FILTER (WHERE b) AS b_count | |
| FROM ( | |
| SELECT | |
| id IN (SELECT id FROM inner_t) AS a, | |
| id IN (SELECT id FROM inner_t WHERE z < 500) AS b | |
| FROM outer_t | |
| ); |