Stefan Holderbach 1bb953877e
Improve select row perf for large N (#10355)
# Description
While reviewing #10350 I noticed that a `HashSet<usize>` was used to
deduplicate the incoming rows, which are then sorted after cloning to a
separate `Vec`. This sounds like a candidate for a `BTreeSet` which
guarantees the ordering.

In the process I removed some dead code.

- Use `BTreeSet` instead of `HashSet`
- Remove dead `skip` logic
- Use `BTreeSet` directly in `NthIterator`
- Consume `BTreeSet` through `Peekable<IntoIter>`
2023-09-21 23:51:13 +02:00
..
2023-09-20 12:57:58 -05:00