summaryrefslogtreecommitdiff
path: root/myisammrg/myrg_rprev.c
blob: 42b23059d13d875d7a0175c34737765d8c64acfa (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
/* Copyright (C) 2000 MySQL AB & MySQL Finland AB & TCX DataKonsult AB

   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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */

#include "myrg_def.h"

	/*
	   Read previous row with the same key as previous read
	*/

int myrg_rprev(MYRG_INFO *info, byte *buf, int inx)
{
  int err;
  MI_INFO *mi;

  if (!info->current_table)
    return (HA_ERR_KEY_NOT_FOUND);

  /* at first, do rprev for the table found before */
  if ((err=mi_rprev(info->current_table->table,NULL,inx)))
  {
    if (err == HA_ERR_END_OF_FILE)
    {
      queue_remove(&(info->by_key),0);
      if (!info->by_key.elements)
        return HA_ERR_END_OF_FILE;
    }
    else
      return err;
  }
  else
  {
    /* Found here, adding to queue */
    queue_top(&(info->by_key))=(byte *)(info->current_table);
    queue_replaced(&(info->by_key));
  }

  /* now, mymerge's read_prev is as simple as one queue_top */
  mi=(info->current_table=(MYRG_TABLE *)queue_top(&(info->by_key)))->table;
  return _myrg_mi_read_record(mi,buf);
}