1 /* Copyright (c) 2000, 2011, Oracle and/or its affiliates. All rights reserved.
2
3 This program is free software; you can redistribute it and/or modify
4 it under the terms of the GNU General Public License, version 2.0,
5 as published by the Free Software Foundation.
6
7 This program is also distributed with certain software (including
8 but not limited to OpenSSL) that is licensed under separate terms,
9 as designated in a particular file or component or in included license
10 documentation. The authors of MySQL hereby grant you an additional
11 permission to link the program and your derivative works with the
12 separately licensed software that they have included with MySQL.
13
14 This program is distributed in the hope that it will be useful,
15 but WITHOUT ANY WARRANTY; without even the implied warranty of
16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 GNU General Public License, version 2.0, for more details.
18
19 You should have received a copy of the GNU General Public License
20 along with this program; if not, write to the Free Software Foundation,
21 51 Franklin Street, Suite 500, Boston, MA 02110-1335 USA */
22
23
24 /**
25 @file
26
27 @brief
28 Buffers to save and compare item values
29 */
30
31 #include "sql_priv.h"
32 /*
33 It is necessary to include set_var.h instead of item.h because there
34 are dependencies on include order for set_var.h and item.h. This
35 will be resolved later.
36 */
37 #include "sql_class.h" // THD
38 #include "set_var.h" // Cached_item, Cached_item_field, ...
39
40 using std::min;
41 using std::max;
42
43 /**
44 Create right type of Cached_item for an item.
45 */
46
new_Cached_item(THD * thd,Item * item,bool use_result_field)47 Cached_item *new_Cached_item(THD *thd, Item *item, bool use_result_field)
48 {
49 if (item->real_item()->type() == Item::FIELD_ITEM &&
50 !(((Item_field *) (item->real_item()))->field->flags & BLOB_FLAG))
51 {
52 Item_field *real_item= (Item_field *) item->real_item();
53 Field *cached_field= use_result_field ? real_item->result_field :
54 real_item->field;
55 return new Cached_item_field(cached_field);
56 }
57 switch (item->result_type()) {
58 case STRING_RESULT:
59 if (item->is_temporal())
60 return new Cached_item_temporal((Item_field *) item);
61 return new Cached_item_str(thd, (Item_field *) item);
62 case INT_RESULT:
63 return new Cached_item_int((Item_field *) item);
64 case REAL_RESULT:
65 return new Cached_item_real(item);
66 case DECIMAL_RESULT:
67 return new Cached_item_decimal(item);
68 case ROW_RESULT:
69 default:
70 DBUG_ASSERT(0);
71 return 0;
72 }
73 }
74
~Cached_item()75 Cached_item::~Cached_item() {}
76
77 /**
78 Compare with old value and replace value with new value.
79
80 @return
81 Return true if values have changed
82 */
83
Cached_item_str(THD * thd,Item * arg)84 Cached_item_str::Cached_item_str(THD *thd, Item *arg)
85 :item(arg),
86 value_max_length(min<uint32>(arg->max_length, thd->variables.max_sort_length)),
87 value(value_max_length)
88 {}
89
cmp(void)90 bool Cached_item_str::cmp(void)
91 {
92 String *res;
93 bool tmp;
94
95 DBUG_ENTER("Cached_item_str::cmp");
96 DBUG_ASSERT(!item->is_temporal());
97 if ((res=item->val_str(&tmp_value)))
98 res->length(min(res->length(), value_max_length));
99 DBUG_PRINT("info", ("old: %s, new: %s",
100 value.c_ptr_safe(), res ? res->c_ptr_safe() : ""));
101 if (null_value != item->null_value)
102 {
103 if ((null_value= item->null_value))
104 DBUG_RETURN(TRUE); // New value was null
105 tmp=TRUE;
106 }
107 else if (null_value)
108 DBUG_RETURN(0); // new and old value was null
109 else
110 tmp= sortcmp(&value,res,item->collation.collation) != 0;
111 if (tmp)
112 value.copy(*res); // Remember for next cmp
113 DBUG_RETURN(tmp);
114 }
115
~Cached_item_str()116 Cached_item_str::~Cached_item_str()
117 {
118 item=0; // Safety
119 }
120
cmp(void)121 bool Cached_item_real::cmp(void)
122 {
123 DBUG_ENTER("Cached_item_real::cmp");
124 double nr= item->val_real();
125 DBUG_PRINT("info", ("old: %f, new: %f", value, nr));
126 if (null_value != item->null_value || nr != value)
127 {
128 null_value= item->null_value;
129 value=nr;
130 DBUG_RETURN(TRUE);
131 }
132 DBUG_RETURN(FALSE);
133 }
134
cmp(void)135 bool Cached_item_int::cmp(void)
136 {
137 DBUG_ENTER("Cached_item_int::cmp");
138 longlong nr=item->val_int();
139 DBUG_PRINT("info", ("old: %lld, new: %lld", value, nr));
140 if (null_value != item->null_value || nr != value)
141 {
142 null_value= item->null_value;
143 value=nr;
144 DBUG_RETURN(TRUE);
145 }
146 DBUG_RETURN(FALSE);
147 }
148
149
cmp(void)150 bool Cached_item_temporal::cmp(void)
151 {
152 DBUG_ENTER("Cached_item_temporal::cmp");
153 longlong nr= item->val_temporal_by_field_type();
154 DBUG_PRINT("info", ("old: %lld, new: %lld", value, nr));
155 if (null_value != item->null_value || nr != value)
156 {
157 null_value= item->null_value;
158 value= nr;
159 DBUG_RETURN(TRUE);
160 }
161 DBUG_RETURN(FALSE);
162 }
163
164
cmp(void)165 bool Cached_item_field::cmp(void)
166 {
167 DBUG_ENTER("Cached_item_field::cmp");
168 DBUG_EXECUTE("info", dbug_print(););
169
170 bool different= false;
171
172 if (field->is_null())
173 {
174 if (!null_value)
175 {
176 different= true;
177 null_value= true;
178 }
179 }
180 else
181 {
182 if (null_value)
183 {
184 different= true;
185 null_value= false;
186 field->get_image(buff, length, field->charset());
187 }
188 else if (field->cmp(buff)) // Not a blob: cmp() is OK
189 {
190 different= true;
191 field->get_image(buff, length, field->charset());
192 }
193 }
194
195 DBUG_RETURN(different);
196 }
197
198
Cached_item_decimal(Item * it)199 Cached_item_decimal::Cached_item_decimal(Item *it)
200 :item(it)
201 {
202 my_decimal_set_zero(&value);
203 }
204
205
cmp()206 bool Cached_item_decimal::cmp()
207 {
208 my_decimal tmp;
209 my_decimal *ptmp= item->val_decimal(&tmp);
210 if (null_value != item->null_value ||
211 (!item->null_value && my_decimal_cmp(&value, ptmp)))
212 {
213 null_value= item->null_value;
214 /* Save only not null values */
215 if (!null_value)
216 {
217 my_decimal2decimal(ptmp, &value);
218 return TRUE;
219 }
220 return FALSE;
221 }
222 return FALSE;
223 }
224