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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
| subject_name | chapter_name | chapter_status | student_id | marked_status |
|---|---|---|---|---|
| Science | Chapter1 | COMPLETED | 6998104_1 | Marked as Complete |
| Science | Chapter2 | COMPLETED | 6998104_1 | Completed |
| Science | Chapter3 | IN_PROGRESS | 6998104_1 | IN_PROGRESS |
| Science | Chapter1 | COMPLETED | 6998103_1 | Marked as Complete |
| Science | Chapter2 | COMPLETED | 6998103_1 | Marked as Complete |
| Science | Chapter3 | COMPLETED | 6998103_1 | Marked as Complete |
| Science | Chapter1 | COMPLETED | 6998102_1 | Completed |
| Science | Chapter2 | COMPLETED | 6998102_1 | Marked as Complete |
| Science | Chapter3 | COMPLETED | 6998102_1 | Marked as Complete |
INSERT 0 9
| subject_name | chapter_name | chapter_status | student_id | marked_status | SUBJECT_STATUS |
|---|---|---|---|---|---|
| Science | Chapter1 | COMPLETED | 6998104_1 | Marked as Complete | IN_PROGRESS |
| Science | Chapter2 | COMPLETED | 6998104_1 | Completed | IN_PROGRESS |
| Science | Chapter3 | IN_PROGRESS | 6998104_1 | IN_PROGRESS | IN_PROGRESS |
| Science | Chapter1 | COMPLETED | 6998103_1 | Marked as Complete | Marked as Complete |
| Science | Chapter2 | COMPLETED | 6998103_1 | Marked as Complete | Marked as Complete |
| Science | Chapter3 | COMPLETED | 6998103_1 | Marked as Complete | Marked as Complete |
| Science | Chapter1 | COMPLETED | 6998102_1 | Completed | Completed |
| Science | Chapter2 | COMPLETED | 6998102_1 | Marked as Complete | Completed |
| Science | Chapter3 | COMPLETED | 6998102_1 | Marked as Complete | Completed |
SELECT 9