felipecrv opened a new pull request, #35750:
URL: https://github.com/apache/arrow/pull/35750
### Rationale for this change
Boolean arrays (bitmaps) used to represent filters in Arrow take 1 bit per
boolean value. If the filter contains long runs, the filter can be run-end
encoded and save even more memory.
Using POPCNT, a bitmap can be scanned efficiently for <64 runs of logical
values, but a run-end encoded array gives the lengths of the run directly and
go beyond word size per run.
These two observations make the case that, for the right dataset, REE
filters can be more efficiently processed in compute kernels.
### What changes are included in this PR?
- [x] `GetFilterOutputSize` can count number of emits from a REE filter
- [x] `GetTakeIndices` can produce an array of logical indices from a REE
filter
- [ ] `"array_filter"` can handle REE filters
- [ ] `"array_take"` can handle REE filters
### Are these changes tested?
Yes.
### Are there any user-facing changes?
Yes.
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