sql_delete.h

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   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */
 
#ifndef SQL_DELETE_INCLUDED
#define SQL_DELETE_INCLUDED
 
#include "my_sqlcommand.h"
#include "my_table_map.h"
#include "sql/sql_cmd_dml.h"  // Sql_cmd_dml
 
class JOIN;
class Select_lex_visitor;
class THD;
class Table_ref;
template <typename T>
class SQL_I_List;
 
class Sql_cmd_delete final : public Sql_cmd_dml {
 public:
  Sql_cmd_delete(bool multitable_arg, SQL_I_List<Table_ref> *delete_tables_arg)
      : multitable(multitable_arg), delete_tables(delete_tables_arg) {}
 
  enum_sql_command sql_command_code() const override {
    return multitable ? SQLCOM_DELETE_MULTI : SQLCOM_DELETE;
  }
 
  bool is_single_table_plan() const override { return !multitable; }
 
  bool accept(THD *thd, Select_lex_visitor *visitor) override;
 
 protected:
  bool precheck(THD *thd) override;
  bool check_privileges(THD *thd) override;
 
  bool prepare_inner(THD *thd) override;
 
  bool execute_inner(THD *thd) override;
 
 private:
  bool delete_from_single_table(THD *thd);
 
  bool multitable;
  /**
    References to tables that are deleted from in a multitable delete statement.
    Only used to track such tables from the parser. In preparation and
    optimization, use the Table_ref::updating property instead.
  */
  SQL_I_List<Table_ref> *delete_tables;
};
 
/// Find out which of the delete target tables can be deleted from immediately
/// while scanning. This is used by the old optimizer *after* the plan has been
/// created. The hypergraph optimizer does not use this function, as it makes
/// the decision about immediate delete *during* planning, not after planning.
table_map GetImmediateDeleteTables(const JOIN *join, table_map delete_tables);
 
/// Checks if the sql_safe_updates option is enabled, and raises an error and
/// returns true if the statement is likely to delete or update a large number
/// of rows. Specifically, it raises an error if there is a full table scan or
/// full index scan of one of the tables deleted from, and there is no LIMIT
/// clause.
bool CheckSqlSafeUpdate(THD *thd, const JOIN *join);
 
#endif /* SQL_DELETE_INCLUDED */