update_rows_iterator.h

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#ifndef SQL_ITERATORS_UPDATE_ROWS_ITERATOR_H_
#define SQL_ITERATORS_UPDATE_ROWS_ITERATOR_H_
 
/* Copyright (c) 2022, 2026, Oracle and/or its affiliates.
 
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License, version 2.0,
   as published by the Free Software Foundation.
 
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   but not limited to OpenSSL) that is licensed under separate terms,
   as designated in a particular file or component or in included license
   documentation.  The authors of MySQL hereby grant you an additional
   permission to link the program and your derivative works with the
   separately licensed software that they have either included with
   the program or referenced in the documentation.
 
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License, version 2.0, for more details.
 
   You should have received a copy of the GNU General Public License
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   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */
 
#include <cassert>
#include <memory>
 
#include "my_alloc.h"
#include "my_base.h"
#include "my_table_map.h"
#include "sql/iterators/row_iterator.h"
#include "sql/sql_list.h"
 
class COPY_INFO;
class Copy_field;
class Item;
class THD;
struct TABLE;
class Table_ref;
template <class T>
class mem_root_deque;
 
/// An iterator that performs updates to rows returned by its child iterator.
class UpdateRowsIterator final : public RowIterator {
 public:
  UpdateRowsIterator(THD *thd, unique_ptr_destroy_only<RowIterator> source,
                     TABLE *outermost_table, TABLE *immediate_table,
                     Table_ref *update_tables, TABLE **tmp_tables,
                     Copy_field *copy_fields,
                     List<TABLE> unupdated_check_opt_tables,
                     COPY_INFO **update_operations,
                     mem_root_deque<Item *> **fields_for_table,
                     mem_root_deque<Item *> **values_for_table,
                     table_map tables_to_get_rowid_for,
                     bool use_semi_consistent_read);
  ~UpdateRowsIterator() override;
  void StartPSIBatchMode() override { m_source->StartPSIBatchMode(); }
  void EndPSIBatchModeIfStarted() override {
    m_source->EndPSIBatchModeIfStarted();
  }
  void SetNullRowFlag([[maybe_unused]] bool is_null_row) override {
    assert(false);
  }
  void UnlockRow() override { assert(false); }
  ha_rows found_rows() const { return m_found_rows; }
  ha_rows updated_rows() const { return m_updated_rows; }
 
 private:
  /// The iterator producing the rows to update.
  unique_ptr_destroy_only<RowIterator> m_source;
  /// The outermost table of the join. It may or may not be one of the tables
  /// being updated.
  TABLE *m_outermost_table;
  /// The table to perform immediate update on, or nullptr if immediate update
  /// is not possible.
  TABLE *m_immediate_table;
  /// Pointer to list of updated tables, linked via 'next_local'.
  Table_ref *m_update_tables;
  /// Temporary tables used to store cached updates.
  TABLE **m_tmp_tables;
  /// Objects that copy the updated values from a temporary table to the update
  /// target table, and perform conversions if the types differ.
  Copy_field *m_copy_fields;
  /// Tables referenced in the CHECK OPTION condition of the updated view
  /// excluding the updated table.
  List<TABLE> m_unupdated_check_opt_tables;
  /// The update operations of each table in m_update_tables (indexed in the
  /// same order as m_update_tables).
  COPY_INFO **m_update_operations;
  /// The fields list decomposed into separate lists per table.
  mem_root_deque<Item *> **m_fields_for_table;
  /// The values list decomposed into separate lists per table.
  mem_root_deque<Item *> **m_values_for_table;
  /// The number of rows matching the WHERE and join conditions.
  ha_rows m_found_rows{0};
  /// The number of rows actually updated.
  ha_rows m_updated_rows{0};
  /// The tables for which handler::position() must be called to get the row ID.
  /// For all other tables, the child iterator has already copied the correct
  /// row ID into handler::ref.
  table_map m_tables_to_get_rowid_for;
  /// Whether semi-consistent reads should be enabled on m_outermost_table.
  bool m_use_semi_consistent_read;
 
  bool DoInit() override;
  int DoRead() override;
 
  /// Perform all the immediate updates for the current row returned by the
  /// join, and buffer row IDs for the non-immediate tables.
  ///
  /// @param[out] trans_safe Gets set to false if a non-transactional table
  ///                        is updated.
  /// @param[out] transactional_tables Gets set to true if a transactional
  ///                                  table is updated.
  /// @return True on error.
  bool DoImmediateUpdatesAndBufferRowIds(bool *trans_safe,
                                         bool *transactional_tables);
 
  /// Perform all the delayed updates.
  ///
  /// @param[in,out] trans_safe Gets set to false if a non-transactional table
  ///                           is updated.
  /// @param[out] transactional_tables Gets set to true if a transactional
  ///                                  table is updated.
  /// @return True on error.
  bool DoDelayedUpdates(bool *trans_safe, bool *transactional_tables);
};
 
#endif  // SQL_ITERATORS_UPDATE_ROWS_ITERATOR_H_