By using db<>fiddle, you agree to license everything you submit by Creative Commons CC0.
Help with an interesting Postgres question: Why isn't an Index Only Scan used on a partition accessed via the parent table?.
CREATE TABLE a (
id text
);
INSERT INTO a VALUES ('A'), ('B'), ('C');
CREATE TABLE b (
id text,
val int
);
INSERT INTO b VALUES ('A',4), ('B', 5), ('B', 6), ('C', 7);
CREATE TABLE c (
id text,
val int
);
INSERT INTO c VALUES ('A', 7), ('B', 8), ('C', 9)
3 rows affected
4 rows affected
3 rows affected
SELECT
a.id,
b.val,
NULL
FROM
a
LEFT JOIN b ON a.id = b.id
UNION ALL
SELECT
a.id,
NULL,
c.val
FROM
a
LEFT JOIN c ON a.id = c.id
ORDER BY 1,2,3
| id | val | ?column? |
|---|---|---|
| A | 4 | null |
| A | null | 7 |
| B | 5 | null |
| B | 6 | null |
| B | null | 8 |
| C | 7 | null |
| C | null | 9 |