jhorstmann opened a new pull request, #9217:
URL: https://github.com/apache/arrow-rs/pull/9217
# Which issue does this PR close?
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- Closes #9216.
# Rationale for this change
Profiling showed this loop to be a clear performance hotspot and thanks to
the new `BooleanBufferBuilder::extend_trusted_len` method introduced in #9137
there is a very simple improvement.
Benchmark results for optional structs after the fix:
```
arrow_array_reader/struct/Int32Array/plain encoded, optional struct,
optional data, no NULLs
time: [69.873 µs 69.917 µs 69.970 µs]
change: [−60.075% −60.046% −60.018%] (p = 0.00 <
0.05)
Performance has improved.
arrow_array_reader/struct/Int32Array/plain encoded, optional struct,
optional data, half NULLs
time: [136.62 µs 136.66 µs 136.72 µs]
change: [−67.663% −67.536% −67.416%] (p = 0.00 <
0.05)
Performance has improved.
```
This is a big improvement, but still significantly slower than reading
non-nested data. The main hotspot still is the `extend_trusted_len` and manual
simd code for comparing chunks and appending 64-bits at a time could
potentially speed it up even more. But that would require either architecture
specific intrinsics or unstable features.
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# What changes are included in this PR?
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# Are these changes tested?
Tested by existing tests.
# Are there any user-facing changes?
no
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