1/* Copyright (c) 2000-2003, 2005-2007 MySQL AB
2 Use is subject to license terms
3
4 This program is free software; you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation; version 2 of the License.
7
8 This program is distributed in the hope that it will be useful,
9 but WITHOUT ANY WARRANTY; without even the implied warranty of
10 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 GNU General Public License for more details.
12
13 You should have received a copy of the GNU General Public License
14 along with this program; if not, write to the Free Software
15 Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA */
16
17#include "myrg_def.h"
18
19 /*
20 Read previous row with the same key as previous read
21 */
22
23int myrg_rprev(MYRG_INFO *info, uchar *buf, int inx)
24{
25 int err;
26 MI_INFO *mi;
27
28 if (!info->current_table)
29 return (HA_ERR_KEY_NOT_FOUND);
30
31 /* at first, do rprev for the table found before */
32 if ((err=mi_rprev(info->current_table->table,NULL,inx)))
33 {
34 if (err == HA_ERR_END_OF_FILE)
35 {
36 queue_remove_top(&(info->by_key));
37 if (!info->by_key.elements)
38 return HA_ERR_END_OF_FILE;
39 }
40 else
41 return err;
42 }
43 else
44 {
45 /* Found here, adding to queue */
46 queue_top(&(info->by_key))=(uchar *)(info->current_table);
47 queue_replace_top(&(info->by_key));
48 }
49
50 /* now, mymerge's read_prev is as simple as one queue_top */
51 mi=(info->current_table=(MYRG_TABLE *)queue_top(&(info->by_key)))->table;
52 return _myrg_mi_read_record(mi,buf);
53}
54