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
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
|
drop table if exists t1;
create table t1 (a int not null,b int not null, primary key using BTREE (a)) engine=heap comment="testing heaps" avg_row_length=100 min_rows=1 max_rows=100;
insert into t1 values(1,1),(2,2),(3,3),(4,4);
delete from t1 where a=1 or a=0;
show keys from t1;
Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment Index_Comment
t1 0 PRIMARY 1 a A NULL NULL NULL BTREE
select * from t1;
a b
2 2
3 3
4 4
select * from t1 where a=4;
a b
4 4
update t1 set b=5 where a=4;
update t1 set b=b+1 where a>=3;
replace t1 values (3,3);
select * from t1;
a b
2 2
3 3
4 6
alter table t1 add c int not null, add key using BTREE (c,a);
drop table t1;
create table t1 (a int not null,b int not null, primary key using BTREE (a)) engine=heap comment="testing heaps";
insert into t1 values(-2,-2),(-1,-1),(0,0),(1,1),(2,2),(3,3),(4,4);
delete from t1 where a > -3;
select * from t1;
a b
drop table t1;
create table t1 (a int not null,b int not null, primary key using BTREE (a)) engine=heap comment="testing heaps";
insert into t1 values(1,1),(2,2),(3,3),(4,4);
alter table t1 modify a int not null auto_increment, engine=myisam, comment="new myisam table";
select * from t1;
a b
1 1
2 2
3 3
4 4
drop table t1;
create table t1 (a int not null) engine=heap;
insert into t1 values (869751),(736494),(226312),(802616),(728912);
select * from t1 where a > 736494;
a
869751
802616
alter table t1 add unique uniq_id using BTREE (a);
select * from t1 where a > 736494;
a
802616
869751
select * from t1 where a = 736494;
a
736494
select * from t1 where a=869751 or a=736494;
a
736494
869751
select * from t1 where a in (869751,736494,226312,802616);
a
226312
736494
802616
869751
alter table t1 engine=myisam;
explain select * from t1 where a in (869751,736494,226312,802616);
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range uniq_id uniq_id 4 NULL 4 Using where; Using index
drop table t1;
create table t1 (x int not null, y int not null, key x using BTREE (x,y), unique y using BTREE (y))
engine=heap;
insert into t1 values (1,1),(2,2),(1,3),(2,4),(2,5),(2,6);
explain select * from t1 where x=1;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref x x 4 const 1
select * from t1 where x=1;
x y
1 1
1 3
select * from t1,t1 as t2 where t1.x=t2.y;
x y x y
1 1 1 1
2 2 2 2
1 3 1 1
2 4 2 2
2 5 2 2
2 6 2 2
explain select * from t1,t1 as t2 where t1.x=t2.y;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL x NULL NULL NULL 6
1 SIMPLE t2 eq_ref y y 4 test.t1.x 1
drop table t1;
create table t1 (a int) engine=heap;
insert into t1 values(1);
select max(a) from t1;
max(a)
1
drop table t1;
CREATE TABLE t1 ( a int not null default 0, b int not null default 0, key using BTREE (a,b), key using BTREE (b) ) ENGINE=HEAP;
insert into t1 values(1,1),(1,2),(2,3),(1,3),(1,4),(1,5),(1,6);
select * from t1 where a=1;
a b
1 1
1 2
1 3
1 4
1 5
1 6
insert into t1 values(1,1),(1,2),(2,3),(1,3),(1,4),(1,5),(1,6);
select * from t1 where a=1;
a b
1 1
1 1
1 2
1 2
1 3
1 3
1 4
1 4
1 5
1 5
1 6
1 6
explain select * from tx where a=x order by a,b;
id select_type table type possible_keys key key_len ref rows Extra
x SIMPLE tx ref a a x const x Using where
explain select * from tx where a=x order by b;
id select_type table type possible_keys key key_len ref rows Extra
x SIMPLE tx ref a a x const x Using where
select * from t1 where b=1;
a b
1 1
1 1
explain select * from tx where b=x;
id select_type table type possible_keys key key_len ref rows Extra
x SIMPLE tx ref b b x const x
drop table t1;
create table t1 (id int unsigned not null, primary key using BTREE (id)) engine=HEAP;
insert into t1 values(1);
select max(id) from t1;
max(id)
1
insert into t1 values(2);
select max(id) from t1;
max(id)
2
replace into t1 values(1);
drop table t1;
create table t1 (n int) engine=heap;
drop table t1;
create table t1 (n int) engine=heap;
drop table if exists t1;
CREATE table t1(f1 int not null,f2 char(20) not
null,index(f2)) engine=heap;
INSERT into t1 set f1=12,f2="bill";
INSERT into t1 set f1=13,f2="bill";
INSERT into t1 set f1=14,f2="bill";
INSERT into t1 set f1=15,f2="bill";
INSERT into t1 set f1=16,f2="ted";
INSERT into t1 set f1=12,f2="ted";
INSERT into t1 set f1=12,f2="ted";
INSERT into t1 set f1=12,f2="ted";
INSERT into t1 set f1=12,f2="ted";
delete from t1 where f2="bill";
select * from t1;
f1 f2
16 ted
12 ted
12 ted
12 ted
12 ted
drop table t1;
create table t1 (btn char(10) not null, key using BTREE (btn)) engine=heap;
insert into t1 values ("hello"),("hello"),("hello"),("hello"),("hello"),("a"),("b"),("c"),("d"),("e"),("f"),("g"),("h"),("i");
explain select * from t1 where btn like "i%";
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range btn btn 12 NULL 1 Using where
explain select * from t1 where btn like "h%";
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range btn btn 12 NULL # Using where
explain select * from t1 where btn like "a%";
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range btn btn 12 NULL 1 Using where
explain select * from t1 where btn like "b%";
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range btn btn 12 NULL 1 Using where
select * from t1 where btn like "ff%";
btn
select * from t1 where btn like " %";
btn
select * from t1 where btn like "q%";
btn
alter table t1 add column new_col char(1) not null, add key using BTREE (btn,new_col), drop key btn;
update t1 set new_col=left(btn,1);
explain select * from t1 where btn="a";
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref btn btn 12 const 1 Using where
explain select * from t1 where btn="a" and new_col="a";
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref btn btn 15 const,const 1 Using where
drop table t1;
CREATE TABLE t1 (
a int default NULL,
b int default NULL,
KEY a using BTREE (a),
UNIQUE b using BTREE (b)
) engine=heap;
INSERT INTO t1 VALUES (NULL,99),(99,NULL),(1,1),(2,2),(1,3);
SELECT * FROM t1 WHERE a=NULL;
a b
explain SELECT * FROM t1 WHERE a IS NULL;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref a a 5 const 1 Using where
SELECT * FROM t1 WHERE a<=>NULL;
a b
NULL 99
SELECT * FROM t1 WHERE b=NULL;
a b
explain SELECT * FROM t1 WHERE b IS NULL;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref b b 5 const 1 Using where
SELECT * FROM t1 WHERE b<=>NULL;
a b
99 NULL
INSERT INTO t1 VALUES (1,3);
ERROR 23000: Duplicate entry '3' for key 'b'
DROP TABLE t1;
CREATE TABLE t1 (a int, b int, c int, key using BTREE (a, b, c)) engine=heap;
INSERT INTO t1 VALUES (1, NULL, NULL), (1, 1, NULL), (1, NULL, 1);
SELECT * FROM t1 WHERE a=1 and b IS NULL;
a b c
1 NULL NULL
1 NULL 1
SELECT * FROM t1 WHERE a=1 and c IS NULL;
a b c
1 NULL NULL
1 1 NULL
SELECT * FROM t1 WHERE a=1 and b IS NULL and c IS NULL;
a b c
1 NULL NULL
DROP TABLE t1;
CREATE TABLE t1 (a int not null, primary key using BTREE (a)) engine=heap;
INSERT into t1 values (1),(2),(3),(4),(5),(6),(7),(8),(9),(10),(11);
DELETE from t1 where a < 100;
SELECT * from t1;
a
DROP TABLE t1;
create table t1(a int not null, key using btree(a)) engine=heap;
insert into t1 values (2), (2), (2), (1), (1), (3), (3), (3), (3);
select a from t1 where a > 2 order by a;
a
3
3
3
3
delete from t1 where a < 4;
select a from t1 order by a;
a
insert into t1 values (2), (2), (2), (1), (1), (3), (3), (3), (3);
select a from t1 where a > 4 order by a;
a
delete from t1 where a > 4;
select a from t1 order by a;
a
1
1
2
2
2
3
3
3
3
select a from t1 where a > 3 order by a;
a
delete from t1 where a >= 2;
select a from t1 order by a;
a
1
1
drop table t1;
CREATE TABLE t1 (
c1 CHAR(3),
c2 INTEGER,
KEY USING BTREE(c1),
KEY USING BTREE(c2)
) ENGINE= MEMORY;
INSERT INTO t1 VALUES ('ABC',0), ('A',0), ('B',0), ('C',0);
UPDATE t1 SET c2= c2 + 1 WHERE c1 = 'A';
SELECT * FROM t1;
c1 c2
ABC 0
A 1
B 0
C 0
DROP TABLE t1;
CREATE TABLE t1 (
c1 ENUM('1', '2'),
UNIQUE USING BTREE(c1)
) ENGINE= MEMORY DEFAULT CHARSET= utf8;
INSERT INTO t1 VALUES('1'), ('2');
DROP TABLE t1;
CREATE TABLE t1 (
c1 SET('1', '2'),
UNIQUE USING BTREE(c1)
) ENGINE= MEMORY DEFAULT CHARSET= utf8;
INSERT INTO t1 VALUES('1'), ('2');
DROP TABLE t1;
CREATE TABLE t1 (a INT, KEY USING BTREE(a)) ENGINE=MEMORY;
INSERT INTO t1 VALUES(1),(2),(2);
DELETE FROM t1 WHERE a=2;
SELECT * FROM t1;
a
1
DROP TABLE t1;
End of 4.1 tests
CREATE TABLE t1(val INT, KEY USING BTREE(val)) ENGINE=memory;
INSERT INTO t1 VALUES(0);
SELECT INDEX_LENGTH FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA=DATABASE() AND TABLE_NAME='t1';
INDEX_LENGTH
21
UPDATE t1 SET val=1;
SELECT INDEX_LENGTH FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA=DATABASE() AND TABLE_NAME='t1';
INDEX_LENGTH
21
DROP TABLE t1;
CREATE TABLE t1 (a INT, UNIQUE USING BTREE(a)) ENGINE=MEMORY;
INSERT INTO t1 VALUES(NULL),(NULL);
DROP TABLE t1;
create table t1(a varchar(255), b varchar(255),
key using btree (a,b)) engine=memory;
insert into t1 values (1, 1), (3, 3), (2, 2), (NULL, 1), (NULL, NULL), (0, 0);
select * from t1 where a is null;
a b
NULL NULL
NULL 1
drop table t1;
End of 5.0 tests
|