doris/be/src/exec/schema_scan_node.h

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// to you under the Apache License, Version 2.0 (the
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//   http://www.apache.org/licenses/LICENSE-2.0
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#ifndef DORIS_BE_SRC_QUERY_EXEC_SCHEMA_SCAN_NODE_H
#define DORIS_BE_SRC_QUERY_EXEC_SCHEMA_SCAN_NODE_H

#include "exec/scan_node.h"
#include "exec/schema_scanner.h"
#include "gen_cpp/Descriptors_types.h"
#include "runtime/descriptors.h"

namespace doris {

class TextConverter;
class Tuple;
class TupleDescriptor;
class RuntimeState;
class MemPool;
class Status;

class SchemaScanNode : public ScanNode {
public:
    SchemaScanNode(ObjectPool* pool, const TPlanNode& tnode, const DescriptorTbl& descs);
    ~SchemaScanNode();

    // Prepare conjuncts, create Schema columns to slots mapping
    // initialize _schema_scanner
    Status init(const TPlanNode& tnode, RuntimeState* state = nullptr) override;

    // Prepare conjuncts, create Schema columns to slots mapping
    // initialize _schema_scanner
    Status prepare(RuntimeState* state) override;

    // Start Schema scan using _schema_scanner.
    Status open(RuntimeState* state) override;

    // Fill the next row batch by calling next() on the _schema_scanner,
    Status get_next(RuntimeState* state, RowBatch* row_batch, bool* eos) override;

    // Close the _schema_scanner, and report errors.
    Status close(RuntimeState* state) override;

    // this is no use in this class
    Status set_scan_ranges(const std::vector<TScanRangeParams>& scan_ranges) override;

private:
    // Write debug string of this into out.
    void debug_string(int indentation_level, std::stringstream* out) const override;
    // Copy one row from schema table to input tuple
    void copy_one_row();
protected:
    bool _is_init;
    const std::string _table_name;
    SchemaScannerParam _scanner_param;
    // Tuple id resolved in prepare() to set _tuple_desc;
    TupleId _tuple_id;

    // Descriptor of tuples read from schema table.
    const TupleDescriptor* _src_tuple_desc;
    // Descriptor of dest tuples
    const TupleDescriptor* _dest_tuple_desc;
    // Tuple index in tuple row.
    int _tuple_idx;
    // slot num need to fill in and return
    int _slot_num;
    // Pool for allocating tuple data, including all varying-length slots.
    std::unique_ptr<MemPool> _tuple_pool;
    // Jni helper for scanning an schema table.
    std::unique_ptr<SchemaScanner> _schema_scanner;
    // Current tuple.
    Tuple* _src_tuple;
    Tuple* _dest_tuple;
    // Map from index in slots to column of schema table.
    std::vector<int> _index_map;
};

} // namespace doris

#endif //__DORIS_MYSQLSCANNODE_H

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