icexelloss commented on code in PR #34311:
URL: https://github.com/apache/arrow/pull/34311#discussion_r1132489205
##########
cpp/src/arrow/compute/exec/options.h:
##########
@@ -199,21 +199,39 @@ class ARROW_EXPORT ProjectNodeOptions : public
ExecNodeOptions {
std::vector<std::string> names;
};
-/// \brief Make a node which aggregates input batches, optionally grouped by
keys.
+/// \brief Make a node which aggregates input batches, optionally grouped by
keys and
+/// optionally segmented by segment-keys. Both keys and segment-keys determine
the group.
+/// However segment-keys are also used for determining grouping segments,
which should be
+/// large, and allow streaming a partial aggregation result after processing
each segment.
+/// One common use-case for segment-keys is ordered aggregation, in which the
segment-key
+/// attribute specifies a column with non-decreasing values or a
lexicographically-ordered
+/// set of such columns.
///
/// If the keys attribute is a non-empty vector, then each aggregate in
`aggregates` is
/// expected to be a HashAggregate function. If the keys attribute is an empty
vector,
/// then each aggregate is assumed to be a ScalarAggregate function.
+///
+/// If the segment_keys attribute is a non-empty vector, then segmented
aggregation, as
+/// described above, applies.
+///
+/// The keys and segment_keys vectors must be disjoint.
+///
+/// See also doc in `aggregate_node.cc`
Review Comment:
@rtpsw Looks like you missed out on this comment
##########
cpp/src/arrow/compute/exec/options.h:
##########
@@ -199,21 +199,39 @@ class ARROW_EXPORT ProjectNodeOptions : public
ExecNodeOptions {
std::vector<std::string> names;
};
-/// \brief Make a node which aggregates input batches, optionally grouped by
keys.
+/// \brief Make a node which aggregates input batches, optionally grouped by
keys and
+/// optionally segmented by segment-keys. Both keys and segment-keys determine
the group.
+/// However segment-keys are also used for determining grouping segments,
which should be
+/// large, and allow streaming a partial aggregation result after processing
each segment.
+/// One common use-case for segment-keys is ordered aggregation, in which the
segment-key
+/// attribute specifies a column with non-decreasing values or a
lexicographically-ordered
+/// set of such columns.
///
/// If the keys attribute is a non-empty vector, then each aggregate in
`aggregates` is
/// expected to be a HashAggregate function. If the keys attribute is an empty
vector,
/// then each aggregate is assumed to be a ScalarAggregate function.
+///
+/// If the segment_keys attribute is a non-empty vector, then segmented
aggregation, as
+/// described above, applies.
+///
+/// The keys and segment_keys vectors must be disjoint.
+///
+/// See also doc in `aggregate_node.cc`
Review Comment:
@rtpsw Looks like you missed out on this comment (minor issue)
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