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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?.
select x.val, count(*) cnt
from (values ('foo / bar / hello'), ('foo / hello'), ('foo / bar')) t(mycol)
cross join lateral regexp_split_to_table(mycol, '\s/\s') as x(val)
group by x.val
| val | cnt |
|---|---|
| bar | 2 |
| foo | 3 |
| hello | 2 |
SELECT 3