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
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
|
/* Copyright (C) 2000-2002 MySQL 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 "heapdef.h"
/* Read next record with the same key */
int heap_rnext(HP_INFO *info, byte *record)
{
byte *pos;
HP_SHARE *share=info->s;
HP_KEYDEF *keyinfo;
DBUG_ENTER("heap_rnext");
if (info->lastinx < 0)
DBUG_RETURN(my_errno=HA_ERR_WRONG_INDEX);
keyinfo = share->keydef + info->lastinx;
if (keyinfo->algorithm == HA_KEY_ALG_BTREE)
{
heap_rb_param custom_arg;
if (info->last_pos)
{
/*
We enter this branch for non-DELETE queries after heap_rkey()
or heap_rfirst(). As last key position (info->last_pos) is available,
we only need to climb the tree using tree_search_next().
*/
pos = tree_search_next(&keyinfo->rb_tree, &info->last_pos,
offsetof(TREE_ELEMENT, left),
offsetof(TREE_ELEMENT, right));
}
else if (!info->lastkey_len)
{
/*
We enter this branch only for DELETE queries after heap_rfirst(). E.g.
DELETE FROM t1 WHERE a<10. As last key position is not available
(last key is removed by heap_delete()), we must restart search as it
is done in heap_rfirst().
It should be safe to handle this situation without this branch. That is
branch below should find smallest element in a tree as lastkey_len is
zero. tree_search_edge() is a kind of optimisation here as it should be
faster than tree_search_key().
*/
pos= tree_search_edge(&keyinfo->rb_tree, info->parents,
&info->last_pos, offsetof(TREE_ELEMENT, left));
}
else
{
/*
We enter this branch only for DELETE queries after heap_rkey(). E.g.
DELETE FROM t1 WHERE a=10. As last key position is not available
(last key is removed by heap_delete()), we must restart search as it
is done in heap_rkey().
*/
custom_arg.keyseg = keyinfo->seg;
custom_arg.key_length = info->lastkey_len;
custom_arg.search_flag = SEARCH_SAME | SEARCH_FIND;
pos = tree_search_key(&keyinfo->rb_tree, info->lastkey, info->parents,
&info->last_pos, info->last_find_flag, &custom_arg);
}
if (pos)
{
memcpy(&pos, pos + (*keyinfo->get_key_length)(keyinfo, pos),
sizeof(byte*));
info->current_ptr = pos;
}
else
{
my_errno = HA_ERR_KEY_NOT_FOUND;
}
}
else
{
if (info->current_hash_ptr)
pos= hp_search_next(info, keyinfo, info->lastkey,
info->current_hash_ptr);
else
{
if (!info->current_ptr && (info->update & HA_STATE_NEXT_FOUND))
{
pos=0; /* Read next after last */
my_errno=HA_ERR_KEY_NOT_FOUND;
}
else if (!info->current_ptr) /* Deleted or first call */
pos= hp_search(info, keyinfo, info->lastkey, 0);
else
pos= hp_search(info, keyinfo, info->lastkey, 1);
}
}
if (!pos)
{
info->update=HA_STATE_NEXT_FOUND; /* For heap_rprev */
if (my_errno == HA_ERR_KEY_NOT_FOUND)
my_errno=HA_ERR_END_OF_FILE;
DBUG_RETURN(my_errno);
}
memcpy(record,pos,(size_t) share->reclength);
info->update=HA_STATE_AKTIV | HA_STATE_NEXT_FOUND;
DBUG_RETURN(0);
}
|
