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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
CREATE TABLE
INSERT 0 10
INSERT 0 100
| year | product_id | total_orders |
|---|---|---|
| 2017-01-01 00:00:00+00 | 1 | 0 |
| 2017-01-01 00:00:00+00 | 2 | 0 |
| 2017-01-01 00:00:00+00 | 3 | 1 |
| 2017-01-01 00:00:00+00 | 4 | 0 |
| 2017-01-01 00:00:00+00 | 5 | 0 |
| 2017-01-01 00:00:00+00 | 6 | 0 |
| 2017-01-01 00:00:00+00 | 7 | 0 |
| 2017-01-01 00:00:00+00 | 8 | 0 |
| 2017-01-01 00:00:00+00 | 9 | 0 |
| 2017-01-01 00:00:00+00 | 10 | 0 |
| 2018-01-01 00:00:00+00 | 1 | 1 |
| 2018-01-01 00:00:00+00 | 2 | 0 |
| 2018-01-01 00:00:00+00 | 3 | 2 |
| 2018-01-01 00:00:00+00 | 4 | 0 |
| 2018-01-01 00:00:00+00 | 5 | 0 |
| 2018-01-01 00:00:00+00 | 6 | 1 |
| 2018-01-01 00:00:00+00 | 7 | 0 |
| 2018-01-01 00:00:00+00 | 8 | 1 |
| 2018-01-01 00:00:00+00 | 9 | 0 |
| 2018-01-01 00:00:00+00 | 10 | 0 |
| 2019-01-01 00:00:00+00 | 1 | 2 |
| 2019-01-01 00:00:00+00 | 2 | 0 |
| 2019-01-01 00:00:00+00 | 3 | 0 |
| 2019-01-01 00:00:00+00 | 4 | 1 |
| 2019-01-01 00:00:00+00 | 5 | 2 |
| 2019-01-01 00:00:00+00 | 6 | 1 |
| 2019-01-01 00:00:00+00 | 7 | 2 |
| 2019-01-01 00:00:00+00 | 8 | 0 |
| 2019-01-01 00:00:00+00 | 9 | 0 |
| 2019-01-01 00:00:00+00 | 10 | 0 |
| 2020-01-01 00:00:00+00 | 1 | 0 |
| 2020-01-01 00:00:00+00 | 2 | 2 |
| 2020-01-01 00:00:00+00 | 3 | 1 |
| 2020-01-01 00:00:00+00 | 4 | 1 |
| 2020-01-01 00:00:00+00 | 5 | 2 |
| 2020-01-01 00:00:00+00 | 6 | 3 |
| 2020-01-01 00:00:00+00 | 7 | 2 |
| 2020-01-01 00:00:00+00 | 8 | 1 |
| 2020-01-01 00:00:00+00 | 9 | 0 |
| 2020-01-01 00:00:00+00 | 10 | 0 |
| 2021-01-01 00:00:00+00 | 1 | 1 |
| 2021-01-01 00:00:00+00 | 2 | 1 |
| 2021-01-01 00:00:00+00 | 3 | 6 |
| 2021-01-01 00:00:00+00 | 4 | 2 |
| 2021-01-01 00:00:00+00 | 5 | 2 |
| 2021-01-01 00:00:00+00 | 6 | 2 |
| 2021-01-01 00:00:00+00 | 7 | 1 |
| 2021-01-01 00:00:00+00 | 8 | 1 |
| 2021-01-01 00:00:00+00 | 9 | 0 |
| 2021-01-01 00:00:00+00 | 10 | 0 |
| 2022-01-01 00:00:00+00 | 1 | 4 |
| 2022-01-01 00:00:00+00 | 2 | 1 |
| 2022-01-01 00:00:00+00 | 3 | 2 |
| 2022-01-01 00:00:00+00 | 4 | 0 |
| 2022-01-01 00:00:00+00 | 5 | 0 |
| 2022-01-01 00:00:00+00 | 6 | 2 |
| 2022-01-01 00:00:00+00 | 7 | 1 |
| 2022-01-01 00:00:00+00 | 8 | 2 |
| 2022-01-01 00:00:00+00 | 9 | 0 |
| 2022-01-01 00:00:00+00 | 10 | 0 |
| 2023-01-01 00:00:00+00 | 1 | 5 |
| 2023-01-01 00:00:00+00 | 2 | 8 |
| 2023-01-01 00:00:00+00 | 3 | 6 |
| 2023-01-01 00:00:00+00 | 4 | 2 |
| 2023-01-01 00:00:00+00 | 5 | 4 |
| 2023-01-01 00:00:00+00 | 6 | 7 |
| 2023-01-01 00:00:00+00 | 7 | 8 |
| 2023-01-01 00:00:00+00 | 8 | 6 |
| 2023-01-01 00:00:00+00 | 9 | 0 |
| 2023-01-01 00:00:00+00 | 10 | 0 |
SELECT 70