filesort.h

/* Copyright (c) 2006, 2018, 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, version 2.0,
   as published by the Free Software Foundation.

   This program is also distributed with certain software (including
   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 included with MySQL.

   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
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */

#ifndef FILESORT_INCLUDED
#define FILESORT_INCLUDED

#include <stddef.h>
#include <sys/types.h>

#include "my_base.h" /* ha_rows */
#include "my_dbug.h"
#include "my_inttypes.h"

class Addon_fields;
class Field;
class QEP_TAB;
class RowIterator;
class Sort_result;
class THD;
struct ORDER;
struct TABLE;
struct st_sort_field;

enum class Addon_fields_status;

/**
  Sorting related info.
*/
class Filesort {
 public:
  /// The QEP entry for the table to be sorted
  QEP_TAB *const qep_tab;
  /// List of expressions to order the table by
  ORDER *order;
  /// Maximum number of rows to return
  ha_rows limit;
  /// ORDER BY list with some precalculated info for filesort
  st_sort_field *sortorder;
  /// true means we are using Priority Queue for order by with limit.
  bool using_pq;
  /// true means force stable sorting
  bool m_force_stable_sort;
  /// Addon fields descriptor
  Addon_fields *addon_fields;

  Filesort(QEP_TAB *tab_arg, ORDER *order_arg, ha_rows limit_arg)
      : Filesort(tab_arg, order_arg, limit_arg, false) {}

  Filesort(QEP_TAB *tab_arg, ORDER *order_arg, ha_rows limit_arg,
           bool force_stable_sort)
      : qep_tab(tab_arg),
        order(order_arg),
        limit(limit_arg),
        sortorder(NULL),
        using_pq(false),
        m_force_stable_sort(
            force_stable_sort),  // keep relative order of equiv. elts
        addon_fields(NULL){};

  /* Prepare ORDER BY list for sorting. */
  uint make_sortorder();

  Addon_fields *get_addon_fields(ulong max_length_for_sort_data,
                                 Field **ptabfield, uint sortlength,
                                 Addon_fields_status *addon_fields_status,
                                 uint *plength, uint *ppackable_length);
};

bool filesort(THD *thd, Filesort *fsort, bool sort_positions,
              RowIterator *source_iterator, Sort_result *sort_result,
              ha_rows *examined_rows, ha_rows *found_rows,
              ha_rows *returned_rows);
void filesort_free_buffers(TABLE *table, bool full);
void change_double_for_sort(double nr, uchar *to);

/// Declared here so we can unit test it.
uint sortlength(THD *thd, st_sort_field *sortorder, uint s_length);

#endif /* FILESORT_INCLUDED */