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
|
/*
Copyright (c) 2000, 2010, Oracle and/or its affiliates.
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., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */
/**
@file
@brief
Buffers to save and compare item values
*/
#include <my_global.h>
#include "sql_priv.h"
/*
It is necessary to include set_var.h instead of item.h because there
are dependencies on include order for set_var.h and item.h. This
will be resolved later.
*/
#include "sql_class.h" // THD
#include "set_var.h" // Cached_item, Cached_item_field, ...
/**
Create right type of Cached_item for an item.
*/
Cached_item *new_Cached_item(THD *thd, Item *item, bool pass_through_ref)
{
if (pass_through_ref && item->real_item()->type() == Item::FIELD_ITEM &&
!(((Item_field *) (item->real_item()))->field->flags & BLOB_FLAG))
{
Item_field *real_item= (Item_field *) item->real_item();
Field *cached_field= real_item->field;
return new (thd->mem_root) Cached_item_field(thd, cached_field);
}
switch (item->result_type()) {
case STRING_RESULT:
return new Cached_item_str(thd, (Item_field *) item);
case INT_RESULT:
return new Cached_item_int((Item_field *) item);
case REAL_RESULT:
return new Cached_item_real(item);
case DECIMAL_RESULT:
return new Cached_item_decimal(item);
case ROW_RESULT:
default:
DBUG_ASSERT(0);
return 0;
}
}
Cached_item::~Cached_item() {}
/**
Compare with old value and replace value with new value.
@return
Return true if values have changed
*/
Cached_item_str::Cached_item_str(THD *thd, Item *arg)
:item(arg),
value_max_length(MY_MIN(arg->max_length, thd->variables.max_sort_length)),
value(value_max_length)
{}
bool Cached_item_str::cmp(void)
{
String *res;
bool tmp;
if ((res=item->val_str(&tmp_value)))
res->length(MY_MIN(res->length(), value_max_length));
if (null_value != item->null_value)
{
if ((null_value= item->null_value))
return TRUE; // New value was null
tmp=TRUE;
}
else if (null_value)
return 0; // new and old value was null
else
tmp= sortcmp(&value,res,item->collation.collation) != 0;
if (tmp)
value.copy(*res); // Remember for next cmp
return tmp;
}
Cached_item_str::~Cached_item_str()
{
item=0; // Safety
}
bool Cached_item_real::cmp(void)
{
double nr= item->val_real();
if (null_value != item->null_value || nr != value)
{
null_value= item->null_value;
value=nr;
return TRUE;
}
return FALSE;
}
bool Cached_item_int::cmp(void)
{
longlong nr=item->val_int();
if (null_value != item->null_value || nr != value)
{
null_value= item->null_value;
value=nr;
return TRUE;
}
return FALSE;
}
bool Cached_item_field::cmp(void)
{
bool tmp= FALSE; // Value is identical
/* Note that field can't be a blob here ! */
if (null_value != field->is_null())
{
null_value= !null_value;
tmp= TRUE; // Value has changed
}
/*
If value is not null and value changed (from null to not null or
becasue of value change), then copy the new value to buffer.
*/
if (! null_value && (tmp || (tmp= (field->cmp(buff) != 0))))
field->get_image(buff,length,field->charset());
return tmp;
}
Cached_item_decimal::Cached_item_decimal(Item *it)
:item(it)
{
my_decimal_set_zero(&value);
}
bool Cached_item_decimal::cmp()
{
my_decimal tmp;
my_decimal *ptmp= item->val_decimal(&tmp);
if (null_value != item->null_value ||
(!item->null_value && my_decimal_cmp(&value, ptmp)))
{
null_value= item->null_value;
/* Save only not null values */
if (!null_value)
{
my_decimal2decimal(ptmp, &value);
return TRUE;
}
return FALSE;
}
return FALSE;
}
|
