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Help with an interesting Postgres question: Why isn't an Index Only Scan used on a partition accessed via the parent table?.
CREATE TABLE data(ID INT,cost_1 INT, quantity_1 INT, cost_2 INT, quantity_2 INT);
INSERT INTO data
VALUES (1,1,2,3,4), (2,3,5,7,9),(3,10,5,20,2);
CREATE TABLE
INSERT 0 3
SELECT ID, cost_1, quantity_1, cost_2, quantity_2, total_1,total_2,
total_1 + total_2 AS total_3
FROM data
,LATERAL (SELECT cost_1 * quantity_1, cost_2 * quantity_2) AS s1(total_1,total_2);
| id | cost_1 | quantity_1 | cost_2 | quantity_2 | total_1 | total_2 | total_3 |
|---|---|---|---|---|---|---|---|
| 1 | 1 | 2 | 3 | 4 | 2 | 12 | 14 |
| 2 | 3 | 5 | 7 | 9 | 15 | 63 | 78 |
| 3 | 10 | 5 | 20 | 2 | 50 | 40 | 90 |
SELECT 3