GH-50260: [C++] Add ComputeLogicalNullCount to ChunkedArray#50261
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goel-skd wants to merge 1 commit into
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GH-50260: [C++] Add ComputeLogicalNullCount to ChunkedArray#50261goel-skd wants to merge 1 commit into
goel-skd wants to merge 1 commit into
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ChunkedArray exposed null_count() but had no equivalent of Array::ComputeLogicalNullCount, forcing callers to hand-roll a loop over chunks to account for logical nulls in types without a validity bitmap (unions, run-end encoded arrays). Add ChunkedArray::ComputeLogicalNullCount() that returns the sum of the per-chunk logical null counts. Like the Array-level method, it is recomputed on every call rather than cached. Covered by a new TestChunkedArray test exercising a validity-bitmap type, an empty chunked array, and a run-end encoded chunked array.
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Rationale for this change
ArrayandArrayDataexposeComputeLogicalNullCount(), which counts logical nulls for types that carry them without a validity bitmap (e.g. unions and run-end encoded arrays).ChunkedArrayonly exposednull_count(), which does not account for those logical nulls, so callers had to hand-roll a loop over the chunks. This PR closes that gap.What changes are included in this PR?
Add
ChunkedArray::ComputeLogicalNullCount(), returning the sum ofArray::ComputeLogicalNullCount()over the chunks. As with theArraylevel method, the value is recomputed on each call rather than cached.Are these changes tested?
Yes. A new
TestChunkedArray.ComputeLogicalNullCounttest covers three cases:a type with a validity bitmap (result matches
null_count()),an empty chunked array, and,
a run-end encoded chunked array (where
null_count()is 0 but the logical null count is not).Are there any user-facing changes?
Yes, this adds a new public method,
ChunkedArray::ComputeLogicalNullCount(). The change is purely additive; no existing APIs are modified.ComputeLogicalNullCountmethod toChunkedArray#50260