be/src/vec/exec/distinct_vaggregation_node.h

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//   http://www.apache.org/licenses/LICENSE-2.0
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#pragma once
#include <cstdint>
#include <memory>

#include "vec/exec/vaggregation_node.h"
#include "vec/exprs/vectorized_agg_fn.h"
#include "vec/exprs/vexpr.h"
#include "vec/exprs/vexpr_context.h"
#include "vec/exprs/vslot_ref.h"

namespace doris {
class TPlanNode;
class DescriptorTbl;
class ObjectPool;
class RuntimeState;

namespace vectorized {

// select c_name from customer union select c_name from customer
// this sql used agg node to get distinct row of c_name,
// so it's could output data when it's inserted into hashmap.
// phase1: (_is_merge:false, _needs_finalize:false, Streaming Preaggregation:true, agg size:0, limit:-1)
// phase2: (_is_merge:false, _needs_finalize:true,  Streaming Preaggregation:false,agg size:0, limit:-1)
class DistinctAggregationNode final : public AggregationNode {
public:
    DistinctAggregationNode(ObjectPool* pool, const TPlanNode& tnode, const DescriptorTbl& descs);
    ~DistinctAggregationNode() override = default;
    Status _distinct_pre_agg_with_serialized_key(Block* in_block, Block* out_block);
    void set_num_rows_returned(int64_t rows) { _num_rows_returned = rows; }
    vectorized::VExprContextSPtrs get_conjuncts() { return _conjuncts; }

private:
    void _emplace_into_hash_table_to_distinct(IColumn::Selector& distinct_row,
                                              ColumnRawPtrs& key_columns, const size_t num_rows);

    char* dummy_mapped_data = nullptr;
    IColumn::Selector _distinct_row;
};
} // namespace vectorized
} // namespace doris