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
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
|
/* 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 */
/* Functions to check if a row is unique */
#include "myisamdef.h"
#include <m_ctype.h>
my_bool mi_check_unique(MI_INFO *info, MI_UNIQUEDEF *def, byte *record,
ha_checksum unique_hash, my_off_t disk_pos)
{
my_off_t lastpos=info->lastpos;
MI_KEYDEF *key= &info->s->keyinfo[def->key];
uchar *key_buff=info->lastkey2;
DBUG_ENTER("mi_check_unique");
mi_unique_store(record+key->seg->start, unique_hash);
_mi_make_key(info,def->key,key_buff,record,0);
if (_mi_search(info,info->s->keyinfo+def->key,key_buff,MI_UNIQUE_HASH_LENGTH,
SEARCH_FIND,info->s->state.key_root[def->key]))
{
info->page_changed=1; /* Can't optimize read next */
info->lastpos= lastpos;
DBUG_RETURN(0); /* No matching rows */
}
for (;;)
{
if (info->lastpos != disk_pos &&
!(*info->s->compare_unique)(info,def,record,info->lastpos))
{
my_errno=HA_ERR_FOUND_DUPP_UNIQUE;
info->errkey= (int) def->key;
info->dupp_key_pos= info->lastpos;
info->page_changed=1; /* Can't optimize read next */
info->lastpos=lastpos;
DBUG_PRINT("info",("Found duplicate"));
DBUG_RETURN(1); /* Found identical */
}
if (_mi_search_next(info,info->s->keyinfo+def->key, info->lastkey,
MI_UNIQUE_HASH_LENGTH, SEARCH_BIGGER,
info->s->state.key_root[def->key]) ||
bcmp(info->lastkey, key_buff, MI_UNIQUE_HASH_LENGTH))
{
info->page_changed=1; /* Can't optimize read next */
info->lastpos=lastpos;
DBUG_RETURN(0); /* end of tree */
}
}
}
/* Calculate a hash for a row */
ha_checksum mi_unique_hash(MI_UNIQUEDEF *def, const byte *record)
{
const byte *pos, *end;
ha_checksum crc= 0;
ulong seed1=0, seed2= 4;
HA_KEYSEG *keyseg;
for (keyseg=def->seg ; keyseg < def->end ; keyseg++)
{
enum ha_base_keytype type=(enum ha_base_keytype) keyseg->type;
uint length=keyseg->length;
if (keyseg->null_bit)
{
if (record[keyseg->null_pos] & keyseg->null_bit)
{
/*
Change crc in a way different from an empty string or 0.
(This is an optimisation; The code will work even if this isn't
done)
*/
crc=((crc << 8) + 511+
(crc >> (8*sizeof(ha_checksum)-8)));
continue;
}
}
pos= record+keyseg->start;
if (keyseg->flag & HA_VAR_LENGTH_PART)
{
uint pack_length= keyseg->bit_start;
uint tmp_length= (pack_length == 1 ? (uint) *(uchar*) pos :
uint2korr(pos));
pos+= pack_length; /* Skip VARCHAR length */
set_if_smaller(length,tmp_length);
}
else if (keyseg->flag & HA_BLOB_PART)
{
uint tmp_length=_mi_calc_blob_length(keyseg->bit_start,pos);
memcpy_fixed((byte*) &pos,pos+keyseg->bit_start,sizeof(char*));
if (!length || length > tmp_length)
length=tmp_length; /* The whole blob */
}
end= pos+length;
if (type == HA_KEYTYPE_TEXT || type == HA_KEYTYPE_VARTEXT1 ||
type == HA_KEYTYPE_VARTEXT2)
{
keyseg->charset->coll->hash_sort(keyseg->charset,
(const uchar*) pos, length, &seed1,
&seed2);
crc^= seed1;
}
else
while (pos != end)
crc=((crc << 8) +
(((uchar) *(uchar*) pos++))) +
(crc >> (8*sizeof(ha_checksum)-8));
}
return crc;
}
/*
Returns 0 if both rows have equal unique value
*/
int mi_unique_comp(MI_UNIQUEDEF *def, const byte *a, const byte *b,
my_bool null_are_equal)
{
const byte *pos_a, *pos_b, *end;
HA_KEYSEG *keyseg;
for (keyseg=def->seg ; keyseg < def->end ; keyseg++)
{
enum ha_base_keytype type=(enum ha_base_keytype) keyseg->type;
uint a_length, b_length;
a_length= b_length= keyseg->length;
/* If part is NULL it's regarded as different */
if (keyseg->null_bit)
{
uint tmp;
if ((tmp=(a[keyseg->null_pos] & keyseg->null_bit)) !=
(uint) (b[keyseg->null_pos] & keyseg->null_bit))
return 1;
if (tmp)
{
if (!null_are_equal)
return 1;
continue;
}
}
pos_a= a+keyseg->start;
pos_b= b+keyseg->start;
if (keyseg->flag & HA_VAR_LENGTH_PART)
{
uint pack_length= keyseg->bit_start;
if (pack_length == 1)
{
a_length= (uint) *(uchar*) pos_a++;
b_length= (uint) *(uchar*) pos_b++;
}
else
{
a_length= uint2korr(pos_a);
b_length= uint2korr(pos_b);
pos_a+= 2; /* Skip VARCHAR length */
pos_b+= 2;
}
set_if_smaller(a_length, keyseg->length); /* Safety */
set_if_smaller(b_length, keyseg->length); /* safety */
}
else if (keyseg->flag & HA_BLOB_PART)
{
/* Only compare 'length' characters if length != 0 */
a_length= _mi_calc_blob_length(keyseg->bit_start,pos_a);
b_length= _mi_calc_blob_length(keyseg->bit_start,pos_b);
/* Check that a and b are of equal length */
if (keyseg->length)
{
/*
This is used in some cases when we are not interested in comparing
the whole length of the blob.
*/
set_if_smaller(a_length, keyseg->length);
set_if_smaller(b_length, keyseg->length);
}
memcpy_fixed((byte*) &pos_a,pos_a+keyseg->bit_start,sizeof(char*));
memcpy_fixed((byte*) &pos_b,pos_b+keyseg->bit_start,sizeof(char*));
}
if (type == HA_KEYTYPE_TEXT || type == HA_KEYTYPE_VARTEXT1 ||
type == HA_KEYTYPE_VARTEXT2)
{
if (mi_compare_text(keyseg->charset, (uchar *) pos_a, a_length,
(uchar *) pos_b, b_length, 0, 1))
return 1;
}
else
{
if (a_length != b_length)
return 1;
end= pos_a+a_length;
while (pos_a != end)
{
if (*pos_a++ != *pos_b++)
return 1;
}
}
}
return 0;
}
|
