materialize_path_parameters.h

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/* Copyright (c) 2020, 2024, Oracle and/or its affiliates.
 
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   it under the terms of the GNU General Public License, version 2.0,
   as published by the Free Software Foundation.
 
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#ifndef MATERIALIZE_PATH_PARAMETERS_H
#define MATERIALIZE_PATH_PARAMETERS_H 1
 
// Split out into its own file to reduce the amount of dependencies on
// access_path.h.
 
#include "sql/mem_root_array.h"
#include "sql/sql_class.h"
 
struct AccessPath;
struct TABLE;
class JOIN;
class Temp_table_param;
class Common_table_expr;
class Query_expression;
 
struct MaterializePathParameters {
  // Corresponds to MaterializeIterator::Operand; see it for documentation.
  struct Operand {
    AccessPath *subquery_path;
    int select_number;
    JOIN *join;
    bool disable_deduplication_by_hash_field;
    bool copy_items;
    Temp_table_param *temp_table_param;
    bool is_recursive_reference;
    /// The block no is the first to be materialized with DISTINCT: for EXCEPT
    /// set operation in a materialization for EXCEPT.
    uint m_first_distinct{0};
    /// The index of this block number
    uint m_operand_idx{0};
    /// The number of materialized blocks, i.e. set operands
    uint m_total_operands{0};
  };
  Mem_root_array<Operand> m_operands;
  Mem_root_array<const AccessPath *> *invalidators;
 
  /// Handle to table to materialize into.
  TABLE *table;
 
  /// If materializing a CTE, points to it (see m_cte), otherwise nullptr.
  Common_table_expr *cte;
 
  /// The query expression we are materializing.
  Query_expression *unit;
 
  /**
      @see JOIN. If we are materializing across JOINs, e.g. derived tables,
      ref_slice should be left at -1.
  */
  int ref_slice;
 
  /**
     True if rematerializing on every Init() call (e.g., because we
     have a dependency on a value from outside the query block).
  */
  bool rematerialize;
 
  /**
     Used for when pushing LIMIT down to MaterializeIterator; this is
     more efficient than having a LimitOffsetIterator above the
     MaterializeIterator, since we can stop materializing when there are
     enough rows. (This is especially important for recursive CTEs.)
     Note that we cannot have a LimitOffsetIterator _below_ the
     MaterializeIterator, as that would count wrong if we have deduplication,
     and would not work at all for recursive CTEs.
     Set to HA_POS_ERROR for no limit.
  */
  ha_rows limit_rows;
 
  /**
     True if this is the top level iterator for a
     materialized derived table transformed from a scalar subquery which needs
     run-time cardinality check.
  */
  bool reject_multiple_rows;
 
  /**
     The context for which deduplication is being used. Note: this
     deduplication is different than the deduplication for UNION which is
     handled separately, not through this enum.
  */
  enum DedupType : uint8_t {
    DEDUP_FOR_DISTINCT,  // materialization is for DISTINCT clause.
    DEDUP_FOR_GROUP_BY,  // materialization is for GROUP BY clause.
    NO_DEDUP             // for anything else, including UNION/INTERSECT.
  };
  DedupType deduplication_reason{NO_DEDUP};
};
 
#endif  // !defined(MATERIALIZE_PATH_PARAMETERS_H)