1/* Copyright (c) 2000, 2002, 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 "heapdef.h"
18
19/* Read next record with the same key */
20
21int heap_rnext(HP_INFO *info, uchar *record)
22{
23 uchar *pos;
24 HP_SHARE *share=info->s;
25 HP_KEYDEF *keyinfo;
26 DBUG_ENTER("heap_rnext");
27
28 if (info->lastinx < 0)
29 DBUG_RETURN(my_errno=HA_ERR_WRONG_INDEX);
30
31 keyinfo = share->keydef + info->lastinx;
32 if (keyinfo->algorithm == HA_KEY_ALG_BTREE)
33 {
34 heap_rb_param custom_arg;
35
36 /* If no active record and last was not deleted */
37 if (!(info->update & (HA_STATE_AKTIV | HA_STATE_NO_KEY |
38 HA_STATE_DELETED)))
39 {
40 if (info->update & HA_STATE_NEXT_FOUND)
41 pos= 0; /* Can't search after last row */
42 else
43 {
44 /* Last was 'prev' before first record; search after first record */
45 pos= tree_search_edge(&keyinfo->rb_tree, info->parents,
46 &info->last_pos, offsetof(TREE_ELEMENT, left));
47 }
48 }
49 else if (info->last_pos)
50 {
51 /*
52 We enter this branch for non-DELETE queries after heap_rkey()
53 or heap_rfirst(). As last key position (info->last_pos) is available,
54 we only need to climb the tree using tree_search_next().
55 */
56 pos = tree_search_next(&keyinfo->rb_tree, &info->last_pos,
57 offsetof(TREE_ELEMENT, left),
58 offsetof(TREE_ELEMENT, right));
59 }
60 else if (!info->lastkey_len)
61 {
62 /*
63 We enter this branch only for DELETE queries after heap_rfirst(). E.g.
64 DELETE FROM t1 WHERE a<10. As last key position is not available
65 (last key is removed by heap_delete()), we must restart search as it
66 is done in heap_rfirst().
67
68 It should be safe to handle this situation without this branch. That is
69 branch below should find smallest element in a tree as lastkey_len is
70 zero. tree_search_edge() is a kind of optimisation here as it should be
71 faster than tree_search_key().
72 */
73 pos= tree_search_edge(&keyinfo->rb_tree, info->parents,
74 &info->last_pos, offsetof(TREE_ELEMENT, left));
75 }
76 else
77 {
78 /*
79 We enter this branch only for DELETE queries after heap_rkey(). E.g.
80 DELETE FROM t1 WHERE a=10. As last key position is not available
81 (last key is removed by heap_delete()), we must restart search as it
82 is done in heap_rkey().
83 */
84 custom_arg.keyseg = keyinfo->seg;
85 custom_arg.key_length = info->lastkey_len;
86 custom_arg.search_flag = SEARCH_SAME | SEARCH_FIND;
87 info->last_find_flag= HA_READ_KEY_OR_NEXT;
88 pos = tree_search_key(&keyinfo->rb_tree, info->lastkey, info->parents,
89 &info->last_pos, info->last_find_flag, &custom_arg);
90 }
91 if (pos)
92 {
93 memcpy(&pos, pos + (*keyinfo->get_key_length)(keyinfo, pos),
94 sizeof(uchar*));
95 info->current_ptr = pos;
96 }
97 else
98 {
99 my_errno = HA_ERR_KEY_NOT_FOUND;
100 }
101 }
102 else
103 {
104 if (info->current_hash_ptr)
105 pos= hp_search_next(info, keyinfo, info->lastkey,
106 info->current_hash_ptr);
107 else
108 {
109 if (!info->current_ptr && (info->update & HA_STATE_NEXT_FOUND))
110 {
111 pos=0; /* Read next after last */
112 my_errno=HA_ERR_KEY_NOT_FOUND;
113 }
114 else if (!info->current_ptr) /* Deleted or first call */
115 pos= hp_search(info, keyinfo, info->lastkey, 0);
116 else
117 pos= hp_search(info, keyinfo, info->lastkey, 1);
118 }
119 }
120 if (!pos)
121 {
122 info->update=HA_STATE_NEXT_FOUND; /* For heap_rprev */
123 if (my_errno == HA_ERR_KEY_NOT_FOUND)
124 my_errno=HA_ERR_END_OF_FILE;
125 DBUG_RETURN(my_errno);
126 }
127 memcpy(record,pos,(size_t) share->reclength);
128 info->update=HA_STATE_AKTIV | HA_STATE_NEXT_FOUND;
129 DBUG_RETURN(0);
130}
131