[GitHub] [arrow] rtpsw commented on a diff in pull request #34311: GH-32884: [C++] Add ordered aggregation

["rtpsw (via GitHub)" <gi...@apache.org>]

rtpsw commented on code in PR #34311:
URL: https://github.com/apache/arrow/pull/34311#discussion_r1116160373


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cpp/src/arrow/compute/row/grouper.h:
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@@ -39,10 +82,19 @@ class ARROW_EXPORT Grouper {
   static Result<std::unique_ptr<Grouper>> Make(const std::vector<TypeHolder>& key_types,
                                                ExecContext* ctx = default_exec_context());
 
-  /// Consume a batch of keys, producing the corresponding group ids as an integer array.
+  /// Consume a batch of keys, producing the corresponding group ids as an integer array,
+  /// over a slice defined by an offset and length, which defaults to the batch length.
+  /// Currently only uint32 indices will be produced, eventually the bit width will only
+  /// be as wide as necessary.
+  virtual Result<Datum> Consume(const ExecSpan& batch, int64_t consume_offset = 0,

Review Comment:
   This supports consuming part of a batch at a time. The boundaries for consuming are determined by [segmentation](https://github.com/apache/arrow/pull/34311#issuecomment-1442318634). When a segment boundary is reached, the segmented aggregation can output the aggregation state accumulated thus far.



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