Fokko opened a new issue, #9427:
URL: https://github.com/apache/arrow-rs/issues/9427
**Is your feature request related to a problem or challenge? Please describe
what you are trying to do.**
While going through the code, @scovich noticed that it allocates a
`vec![false; n]` to be appended to the null buffer, which is not very efficent:
```
append_nulls: vec![false; n] (old) vs append_n_nulls (new)
┌─────────┬─────────────────┬──────────────────────┬─────────┐
│ n │ old (vec alloc) │ new (append_n_nulls) │ speedup │
├─────────┼─────────────────┼──────────────────────┼─────────┤
│ 100 │ 82 ns │ 43 ns │ ~2x │
├─────────┼─────────────────┼──────────────────────┼─────────┤
│ 1,000 │ 319 ns │ 47 ns │ ~7x │
├─────────┼─────────────────┼──────────────────────┼─────────┤
│ 10,000 │ 2,540 ns │ 68 ns │ ~37x │
├─────────┼─────────────────┼──────────────────────┼─────────┤
│ 100,000 │ 25,526 ns │ 293 ns │ ~87x │
└─────────┴─────────────────┴──────────────────────┴─────────┘
```
**Describe the solution you'd like**
Don't allocate the buffer, and pass it down to the bitmap.
**Describe alternatives you've considered**
∅
**Additional context**
∅
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