text: #ifndef SQL_TRUNCATE_INCLUDED
  #define SQL_TRUNCATE_INCLUDED
  /* Copyright (c) 2010, 2015, Oracle and/or its affiliates. All rights reserved.
  
     This program is free software; you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published by
     the Free Software Foundation; version 2 of the License.
  
     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 for more details.
  
     You should have received a copy of the GNU General Public License
     along with this program; if not, write to the Free Software
     Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */
  
  #include "my_global.h"
  #include "sql_cmd_dml.h"          // Sql_cmd_dml
  
  class MDL_ticket;
  class THD;
  struct TABLE_LIST;
  
  /**
    Sql_cmd_truncate_table represents the TRUNCATE statement.
  */
  class Sql_cmd_truncate_table : public Sql_cmd_dml
  {
  private:
    /* Set if a lock must be downgraded after truncate is done. */
    MDL_ticket *m_ticket_downgrade;
  
  public:
    /**
      Constructor, used to represent a TRUNCATE statement.
    */
    Sql_cmd_truncate_table()
    {}
  
    virtual ~Sql_cmd_truncate_table()
    {}
  
    /**
      Execute a TRUNCATE statement at runtime.
      @param thd the current thread.
      @return false on success.
    */
    bool execute(THD *thd);
  
    virtual enum_sql_command sql_command_code() const
    {
      return SQLCOM_TRUNCATE;
    }
  
    virtual bool prepared_statement_test(THD *) { return false; }
    virtual bool prepare(THD *) { return false; }
    virtual void cleanup(THD *) {}
  
  protected:
    enum truncate_result{
      TRUNCATE_OK=0,
      TRUNCATE_FAILED_BUT_BINLOG,
      TRUNCATE_FAILED_SKIP_BINLOG
    };
  
    /** Handle locking a base table for truncate. */
    bool lock_table(THD *, TABLE_LIST *, bool *);
  
    /** Truncate table via the handler method. */
    enum truncate_result handler_truncate(THD *, TABLE_LIST *, bool);
  
    /**
      Optimized delete of all rows by doing a full regenerate of the table.
      Depending on the storage engine, it can be accomplished through a
      drop and recreate or via the handler truncate method.
    */
    bool truncate_table(THD *, TABLE_LIST *);
  };
  
  #endif
  