icexelloss commented on code in PR #34912:
URL: https://github.com/apache/arrow/pull/34912#discussion_r1173127725
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cpp/src/arrow/compute/kernels/hash_aggregate.cc:
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@@ -1695,6 +1692,384 @@ struct GroupedMinMaxFactory {
InputType argument_type;
};
+// ----------------------------------------------------------------------
+// FirstLast implementation
+
+template <typename Type, typename Enable = void>
+struct GroupedFirstLastImpl final : public GroupedAggregator {
+ using CType = typename TypeTraits<Type>::CType;
+ using GetSet = GroupedValueTraits<Type>;
+ using ArrType =
+ typename std::conditional<is_boolean_type<Type>::value, uint8_t,
CType>::type;
+
+ Status Init(ExecContext* ctx, const KernelInitArgs& args) override {
+ options_ = *checked_cast<const ScalarAggregateOptions*>(args.options);
+
+ firsts_ = TypedBufferBuilder<CType>(ctx->memory_pool());
+ lasts_ = TypedBufferBuilder<CType>(ctx->memory_pool());
+ has_values_ = TypedBufferBuilder<bool>(ctx->memory_pool());
+ has_nulls_ = TypedBufferBuilder<bool>(ctx->memory_pool());
+ return Status::OK();
+ }
+
+ Status Resize(int64_t new_num_groups) override {
+ auto added_groups = new_num_groups - num_groups_;
+ num_groups_ = new_num_groups;
+ // Reusing AntiExtrema as uninitialized value here because it doesn't
+ // matter what the value is. We never output the uninitialized
+ // first/last value.
+ RETURN_NOT_OK(firsts_.Append(added_groups,
AntiExtrema<CType>::anti_min()));
+ RETURN_NOT_OK(lasts_.Append(added_groups, AntiExtrema<CType>::anti_max()));
+ RETURN_NOT_OK(has_values_.Append(added_groups, false));
+ RETURN_NOT_OK(has_nulls_.Append(added_groups, false));
+ return Status::OK();
+ }
+
+ Status Consume(const ExecSpan& batch) override {
Review Comment:
(Consume, Merge and Finalize)
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