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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?.
WITH yourTable AS (
SELECT 1 AS value UNION ALL
SELECT 2 UNION ALL
SELECT 3
),
cte AS (
SELECT value, ROW_NUMBER() OVER (ORDER BY value) rn
FROM yourTable
)
SELECT
MAX(value) FILTER (WHERE rn = 1) AS tmp,
MAX(value) FILTER (WHERE rn = 2) AS tmp02,
MAX(value) FILTER (WHERE rn = 3) AS tmp03
FROM cte;
| tmp | tmp02 | tmp03 |
|---|---|---|
| 1 | 2 | 3 |
SELECT 1