perf: Improve efficiency of array_resize for sliced arrays - #25479
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## main #25479 +/- ##
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+ Coverage 82.34% 82.38% +0.04%
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Files 1137 1138 +1
Lines 432364 433776 +1412
Branches 432364 433776 +1412
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jayzhan211
approved these changes
Sep 19, 2026
jayzhan211
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Thanks @neilconway , all minor suggestions
| let count = O::usize_as(count); | ||
| let start = offset_window[0]; | ||
| if start + count > offset_window[1] { | ||
| debug_assert!( |
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debug_assert! is compiled out in release; a violated invariant then becomes an index-OOB panic inside MutableArrayData::try_extend(1, ..). Return an internal error instead:
- debug_assert!(
- default_value_data.is_some(),
- "fill values are required when growing a list"
- );
+ if default_value_data.is_none() {
+ return internal_err!(
+ "array_resize: fill values are required when growing a list"
+ );
+ }
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Which issue does this PR close?
Rationale for this change
array_resizeprepares fill/padding values for the situations in which it needs to grow the input arrays. When (a) no fill value was provided, and (b) no row needs to grow, the code allocated an all-NULL array equal to the size of the underlying backing array of the to-be-resized input. This is redundant, because no fill is needed; it's also potentially expensive, because the backing array might be much larger than the actual visible portion of the input.Benchmarks:
Other benchmark cases were within noise.
What changes are included in this PR?
build_resized_listto make the fill dataOptionalWhat is the testing strategy for this PR?
Benchmarked to confirm performance improvement. Existing tests pass. Added new unit tests to improve code coverage; they are not intended to catch the allocation change though.
Are there any user-facing changes?
No.