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
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
|
/* 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; either version 2 of the License, or
(at your option) any later version.
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 */
/*
Gives a approximated number of how many records there is between two keys.
Used when optimizing querries.
*/
#include "isamdef.h"
static ulong _nisam_record_pos(N_INFO *info,const byte *key,uint key_len,
enum ha_rkey_function search_flag);
static double _nisam_search_pos(N_INFO *info,N_KEYDEF *keyinfo,uchar *key,
uint key_len,uint nextflag,ulong pos);
static uint _nisam_keynr(N_INFO *info,N_KEYDEF *keyinfo,uchar *page,
uchar *keypos,uint *ret_max_key);
/* If start_key = 0 assume read from start */
/* If end_key = 0 assume read to end */
/* Returns NI_POS_ERROR on error */
ulong nisam_records_in_range(N_INFO *info, int inx, const byte *start_key,
uint start_key_len,
enum ha_rkey_function start_search_flag,
const byte *end_key, uint end_key_len,
enum ha_rkey_function end_search_flag)
{
ulong start_pos,end_pos;
DBUG_ENTER("nisam_records_in_range");
if ((inx = _nisam_check_index(info,inx)) < 0)
DBUG_RETURN(NI_POS_ERROR);
#ifndef NO_LOCKING
if (_nisam_readinfo(info,F_RDLCK,1))
DBUG_RETURN(NI_POS_ERROR);
#endif
info->update&= (HA_STATE_CHANGED | HA_STATE_ROW_CHANGED);
start_pos= (start_key ?
_nisam_record_pos(info,start_key,start_key_len,start_search_flag) :
0L);
end_pos= (end_key ?
_nisam_record_pos(info,end_key,end_key_len,end_search_flag) :
info->s->state.records+1L);
VOID(_nisam_writeinfo(info,0));
if (start_pos == NI_POS_ERROR || end_pos == NI_POS_ERROR)
DBUG_RETURN(NI_POS_ERROR);
DBUG_PRINT("info",("records: %ld",end_pos-start_pos));
DBUG_RETURN(end_pos < start_pos ? 0L :
(end_pos == start_pos ? 1L : end_pos-start_pos));
}
/* Find relative position (in records) for key in index-tree */
static ulong _nisam_record_pos(N_INFO *info, const byte *key, uint key_len,
enum ha_rkey_function search_flag)
{
uint inx=(uint) info->lastinx;
N_KEYDEF *keyinfo=info->s->keyinfo+inx;
uchar *key_buff;
double pos;
DBUG_ENTER("_nisam_record_pos");
DBUG_PRINT("enter",("search_flag: %d",search_flag));
if (key_len >= (keyinfo->base.keylength-info->s->rec_reflength)
&& !(keyinfo->base.flag & HA_SPACE_PACK_USED))
key_len=USE_HOLE_KEY;
key_buff=info->lastkey+info->s->base.max_key_length;
key_len=_nisam_pack_key(info,inx,key_buff,(uchar*) key,key_len);
DBUG_EXECUTE("key",_nisam_print_key(DBUG_FILE,keyinfo->seg,
(uchar*) key_buff););
pos=_nisam_search_pos(info,keyinfo,key_buff,key_len,
nisam_read_vec[search_flag] | SEARCH_SAVE_BUFF,
info->s->state.key_root[inx]);
if (pos >= 0.0)
{
DBUG_PRINT("exit",("pos: %ld",(ulong) (pos*info->s->state.records)));
DBUG_RETURN((ulong) (pos*info->s->state.records+0.5));
}
DBUG_RETURN(NI_POS_ERROR);
}
/* This is a modified version of _nisam_search */
/* Returns offset for key in indextable (decimal 0.0 <= x <= 1.0) */
static double _nisam_search_pos(register N_INFO *info, register N_KEYDEF *keyinfo,
uchar *key, uint key_len, uint nextflag,
register ulong pos)
{
int flag;
uint nod_flag,keynr,max_keynr;
uchar *keypos,*buff;
double offset;
DBUG_ENTER("_nisam_search_pos");
if (pos == NI_POS_ERROR)
DBUG_RETURN(0.5);
if (!(buff=_nisam_fetch_keypage(info,keyinfo,pos,info->buff,1)))
goto err;
flag=(*keyinfo->bin_search)(info,keyinfo,buff,key,key_len,nextflag,
&keypos,info->lastkey);
nod_flag=test_if_nod(buff);
keynr=_nisam_keynr(info,keyinfo,buff,keypos,&max_keynr);
if (flag)
{
/*
** Didn't found match. keypos points at next (bigger) key
* Try to find a smaller, better matching key.
** Matches keynr + [0-1]
*/
if ((offset=_nisam_search_pos(info,keyinfo,key,key_len,nextflag,
_nisam_kpos(nod_flag,keypos))) < 0)
DBUG_RETURN(offset);
}
else
{
/*
** Found match. Keypos points at the start of the found key
** Matches keynr+1
*/
offset=1.0; /* Matches keynr+1 */
if (nextflag & SEARCH_FIND && (!(keyinfo->base.flag & HA_NOSAME)
|| key_len) && nod_flag)
{
/*
** There may be identical keys in the tree. Try to match on of those.
** Matches keynr + [0-1]
*/
if ((offset=_nisam_search_pos(info,keyinfo,key,key_len,SEARCH_FIND,
_nisam_kpos(nod_flag,keypos))) < 0)
DBUG_RETURN(offset); /* Read error */
}
}
DBUG_PRINT("info",("keynr: %d offset: %g max_keynr: %d nod: %d flag: %d",
keynr,offset,max_keynr,nod_flag,flag));
DBUG_RETURN((keynr+offset)/(max_keynr+1));
err:
DBUG_PRINT("exit",("Error: %d",my_errno));
DBUG_RETURN (-1.0);
}
/* Get keynummer of current key and max number of keys in nod */
static uint _nisam_keynr(N_INFO *info, register N_KEYDEF *keyinfo, uchar *page, uchar *keypos, uint *ret_max_key)
{
uint nod_flag,keynr,max_key;
uchar t_buff[N_MAX_KEY_BUFF],*end;
end= page+getint(page);
nod_flag=test_if_nod(page);
page+=2+nod_flag;
if (!(keyinfo->base.flag &
(HA_PACK_KEY | HA_SPACE_PACK | HA_SPACE_PACK_USED)))
{
*ret_max_key= (uint) (end-page)/(keyinfo->base.keylength+nod_flag);
return (uint) (keypos-page)/(keyinfo->base.keylength+nod_flag);
}
max_key=keynr=0;
while (page < end)
{
t_buff[0]=0; /* Don't move packed key */
VOID((*keyinfo->get_key)(keyinfo,nod_flag,&page,t_buff));
max_key++;
if (page == keypos)
keynr=max_key;
}
*ret_max_key=max_key;
return(keynr);
}
|
