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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?.
| version |
|---|
| PostgreSQL 12.14 on x86_64-pc-linux-gnu, compiled by gcc (GCC) 8.5.0 20210514 (Red Hat 8.5.0-16), 64-bit |
SELECT 1
CREATE TABLE
INSERT 0 2
| the_date |
|---|
| 2021-08-29 00:00:00+01 |
| 2021-08-30 00:00:00+01 |
| 2021-08-31 00:00:00+01 |
| 2021-09-01 00:00:00+01 |
| 2021-09-02 00:00:00+01 |
| 2021-09-03 00:00:00+01 |
| 2021-09-04 00:00:00+01 |
| 2021-09-05 00:00:00+01 |
| 2021-09-06 00:00:00+01 |
| 2021-09-07 00:00:00+01 |
| 2021-09-08 00:00:00+01 |
| 2021-09-09 00:00:00+01 |
| 2021-09-10 00:00:00+01 |
| 2021-09-11 00:00:00+01 |
| 2021-09-12 00:00:00+01 |
| 2021-09-13 00:00:00+01 |
| 2021-09-14 00:00:00+01 |
| 2021-09-15 00:00:00+01 |
| 2021-09-16 00:00:00+01 |
| 2021-09-17 00:00:00+01 |
| 2021-09-18 00:00:00+01 |
| 2021-09-19 00:00:00+01 |
| 2021-09-20 00:00:00+01 |
| 2021-09-21 00:00:00+01 |
| 2021-09-22 00:00:00+01 |
| 2021-09-23 00:00:00+01 |
| 2021-09-24 00:00:00+01 |
| 2021-09-25 00:00:00+01 |
| 2021-09-26 00:00:00+01 |
| 2021-09-27 00:00:00+01 |
| 2021-09-28 00:00:00+01 |
| 2021-09-29 00:00:00+01 |
SELECT 32
| the_date | date_part | to_char |
|---|---|---|
| 2021-08-30 00:00:00+01 | 1 | Monday |
| 2021-08-31 00:00:00+01 | 2 | Tuesday |
| 2021-09-01 00:00:00+01 | 3 | Wednesday |
| 2021-09-02 00:00:00+01 | 4 | Thursday |
| 2021-09-03 00:00:00+01 | 5 | Friday |
| 2021-09-06 00:00:00+01 | 1 | Monday |
| 2021-09-07 00:00:00+01 | 2 | Tuesday |
| 2021-09-08 00:00:00+01 | 3 | Wednesday |
| 2021-09-09 00:00:00+01 | 4 | Thursday |
| 2021-09-10 00:00:00+01 | 5 | Friday |
| 2021-09-13 00:00:00+01 | 1 | Monday |
| 2021-09-14 00:00:00+01 | 2 | Tuesday |
| 2021-09-15 00:00:00+01 | 3 | Wednesday |
| 2021-09-16 00:00:00+01 | 4 | Thursday |
| 2021-09-17 00:00:00+01 | 5 | Friday |
| 2021-09-20 00:00:00+01 | 1 | Monday |
| 2021-09-21 00:00:00+01 | 2 | Tuesday |
| 2021-09-22 00:00:00+01 | 3 | Wednesday |
| 2021-09-23 00:00:00+01 | 4 | Thursday |
| 2021-09-24 00:00:00+01 | 5 | Friday |
| 2021-09-27 00:00:00+01 | 1 | Monday |
| 2021-09-28 00:00:00+01 | 2 | Tuesday |
| 2021-09-29 00:00:00+01 | 3 | Wednesday |
SELECT 23