aucahuasi commented on a change in pull request #11257:
URL: https://github.com/apache/arrow/pull/11257#discussion_r718524617
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File path: cpp/src/arrow/compute/kernels/aggregate_basic.cc
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@@ -121,6 +122,84 @@ Result<std::unique_ptr<KernelState>>
CountInit(KernelContext*,
static_cast<const CountOptions&>(*args.options));
}
+// ----------------------------------------------------------------------
+// Distinct Count implementation
+
+template <typename Type>
+struct CountDistinctImpl : public ScalarAggregator {
+ using MemoTable = typename arrow::internal::HashTraits<Type>::MemoTableType;
+
+ explicit CountDistinctImpl(MemoryPool* memory_pool, CountOptions options)
+ : options(std::move(options)), memo_table_(new MemoTable(memory_pool,
0)) {}
+
+ Status Consume(KernelContext*, const ExecBatch& batch) override {
+ if (batch[0].is_array()) {
+ const ArrayData& arr = *batch[0].array();
+ auto visit_null = [&]() {
+ if (this->nulls > 0) return Status::OK();
+ ++this->nulls;
+ return Status::OK();
+ };
Review comment:
Yeah I was thinking about this as well. Would be great to have a visit
call only for non nulls and if the array has null I would just add 1 to the
output.
Thanks for the feedback, let me try to improve this part.
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