icexelloss commented on code in PR #13880:
URL: https://github.com/apache/arrow/pull/13880#discussion_r954254245
##########
cpp/src/arrow/compute/exec/asof_join_node.cc:
##########
@@ -137,18 +173,88 @@ struct MemoStore {
}
};
+// a specialized higher-performance variation of Hashing64 logic from
hash_join_node
+// the code here avoids recreating objects that are independent of each batch
processed
+class KeyHasher {
+ static constexpr int kMiniBatchLength = util::MiniBatch::kMiniBatchLength;
+
+ public:
+ explicit KeyHasher(const vec_col_index_t& indices)
+ : indices_(indices),
+ metadata_(indices.size()),
+ batch_(NULLPTR),
+ hashes_(),
+ ctx_(),
+ column_arrays_(),
+ stack_() {
+ ctx_.stack = &stack_;
+ column_arrays_.resize(indices.size());
+ }
+
+ Status Init(ExecContext* exec_context, const std::shared_ptr<arrow::Schema>&
schema) {
+ ctx_.hardware_flags = exec_context->cpu_info()->hardware_flags();
+ const auto& fields = schema->fields();
+ for (size_t k = 0; k < metadata_.size(); k++) {
+ ARROW_ASSIGN_OR_RAISE(metadata_[k],
+
ColumnMetadataFromDataType(fields[indices_[k]]->type()));
+ }
+ return stack_.Init(exec_context->memory_pool(),
+ 4 * kMiniBatchLength * sizeof(uint32_t));
Review Comment:
What does `4 * kMiniBatchLength * sizeof(uint32_t)` mean here and why pick
this value?
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