feat: Add RowSelection::total_row_count - #10704
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Thank you @haohuaijin and @Rich-T-kid -- this makes sense to me
I also took the liberty of updating some tests to use the new method to add some additional test coverage
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RowSelection::total_row_count
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Thanks @Rich-T-kid @alamb |
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# Which issue does this PR close? - Part of apache#10624. # Rationale for this change `RowSelection` exposes `row_count()` (selected rows) and `skipped_row_count()` (skipped rows), but no way to get the total number of rows a selection spans. Callers that need the total (e.g. to validate a selection against a row group's row count, as apache#10702 does) must call both methods, which iterates a selector-backed selection twice and performs two popcounts on a mask-backed selection just to have them cancel out. # What changes are included in this PR? Adds `RowSelection::total_row_count()`, which computes the total in a single pass: - selector-backed: one sum over the selectors - mask-backed: `mask.len()`, O(1) with no popcount # Are these changes tested? Yes, a unit test covers both backings plus the empty selection. # Are there any user-facing changes? New public method `RowSelection::total_row_count()`. No changes to existing APIs. --------- Co-authored-by: Andrew Lamb <andrew@nerdnetworks.org>
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Which issue does this PR close?
Rationale for this change
RowSelectionexposesrow_count()(selected rows) andskipped_row_count()(skipped rows), but no way to get the total number of rows a selection spans. Callers that need the total (e.g. to validate a selection against a row group's row count, as #10702 does) must call both methods, which iterates a selector-backed selection twice and performs two popcounts on a mask-backed selection just to have them cancel out.What changes are included in this PR?
Adds
RowSelection::total_row_count(), which computes the total in a single pass:mask.len(), O(1) with no popcountAre these changes tested?
Yes, a unit test covers both backings plus the empty selection.
Are there any user-facing changes?
New public method
RowSelection::total_row_count(). No changes to existing APIs.