Method MergeFrom

cpp/src/arrow/compute/kernels/aggregate_basic.cc:192–198

  }

  Status MergeFrom(KernelContext*, KernelState&& src) override {
    const auto& other_state = checked_cast<const CountDistinctImpl&>(src);
    RETURN_NOT_OK(this->memo_table_->MergeTable(*(other_state.memo_table_)));
    this->non_nulls = this->memo_table_->size();
    this->has_nulls = this->has_nulls || other_state.has_nulls;
    return Status::OK();
  }

  Status Finalize(KernelContext* ctx, Datum* out) override {
    const auto& state = checked_cast<const CountDistinctImpl&>(*ctx->state());