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
|
DROP TABLE IF EXISTS t1, t2;
set @save_tmp_table_size=@@tmp_table_size;
set @save_max_heap_table_size=@@max_heap_table_size;
set @save_storage_engine=@@storage_engine;
set storage_engine=MYISAM;
CREATE TABLE t1 (id INTEGER);
CREATE TABLE t2 (id INTEGER);
INSERT INTO t1 (id) VALUES (1), (1), (1),(1);
INSERT INTO t1 (id) SELECT id FROM t1;
/* 8 */
INSERT INTO t1 (id) SELECT id FROM t1;
/* 12 */
INSERT INTO t1 (id) SELECT id FROM t1;
/* 16 */
INSERT INTO t1 (id) SELECT id FROM t1;
/* 20 */
INSERT INTO t1 (id) SELECT id FROM t1;
/* 24 */
INSERT INTO t1 SELECT id+1 FROM t1;
INSERT INTO t1 SELECT id+2 FROM t1;
INSERT INTO t1 SELECT id+4 FROM t1;
INSERT INTO t1 SELECT id+8 FROM t1;
INSERT INTO t1 SELECT id+16 FROM t1;
INSERT INTO t1 SELECT id+32 FROM t1;
INSERT INTO t1 SELECT id+64 FROM t1;
INSERT INTO t1 SELECT id+128 FROM t1;
INSERT INTO t1 SELECT id+256 FROM t1;
INSERT INTO t1 SELECT id+512 FROM t1;
SELECT AVG(DISTINCT id) FROM t1 GROUP BY id % 13;
AVG(DISTINCT id)
513.5000
508.0000
509.0000
510.0000
511.0000
512.0000
513.0000
514.0000
515.0000
516.0000
517.0000
511.5000
512.5000
SELECT SUM(DISTINCT id)/COUNT(DISTINCT id) FROM t1 GROUP BY id % 13;
SUM(DISTINCT id)/COUNT(DISTINCT id)
513.5000
508.0000
509.0000
510.0000
511.0000
512.0000
513.0000
514.0000
515.0000
516.0000
517.0000
511.5000
512.5000
INSERT INTO t1 SELECT id+1024 FROM t1;
INSERT INTO t1 SELECT id+2048 FROM t1;
INSERT INTO t1 SELECT id+4096 FROM t1;
INSERT INTO t1 SELECT id+8192 FROM t1;
INSERT INTO t2 SELECT id FROM t1 ORDER BY id*rand();
SELECT SUM(DISTINCT id) sm FROM t1;
sm
134225920
SELECT SUM(DISTINCT id) sm FROM t2;
sm
134225920
SELECT SUM(DISTINCT id) sm FROM t1 group by id % 13;
sm
10327590
10328851
10330112
10331373
10332634
10317510
10318770
10320030
10321290
10322550
10323810
10325070
10326330
SET max_heap_table_size=16384;
SHOW variables LIKE 'max_heap_table_size';
Variable_name Value
max_heap_table_size 16384
SELECT SUM(DISTINCT id) sm FROM t1;
sm
134225920
SELECT SUM(DISTINCT id) sm FROM t2;
sm
134225920
SELECT SUM(DISTINCT id) sm FROM t1 GROUP BY id % 13;
sm
10327590
10328851
10330112
10331373
10332634
10317510
10318770
10320030
10321290
10322550
10323810
10325070
10326330
#
# Bug mdev-4063: SUM(DISTINCT...) with small'max_heap_table_size
# (bug #56927)
#
SET max_heap_table_size=default;
INSERT INTO t1 SELECT id+16384 FROM t1;
DELETE FROM t2;
INSERT INTO t2 SELECT id FROM t1 ORDER BY id*rand();
SELECT SUM(DISTINCT id) sm FROM t2;
sm
536887296
SET max_heap_table_size=16384;
SELECT SUM(DISTINCT id) sm FROM t2;
sm
536887296
DROP TABLE t1;
DROP TABLE t2;
SET @@tmp_table_size=@save_tmp_table_size;
SET @@max_heap_table_size=@save_max_heap_table_size;
#
# Bug mdev-4311: COUNT(DISTINCT...) requiring a file for Unique
# (bug #68749)
#
set @save_storage_engine=@@storage_engine;
set storage_engine=INNODB;
CREATE TABLE t1 (id INTEGER) ENGINE=InnoDB;
CREATE TABLE t2 (id INTEGER) ENGINE=InnoDB;
INSERT INTO t1 (id) VALUES (1), (1), (1),(1);
INSERT INTO t1 (id) SELECT id FROM t1;
INSERT INTO t1 (id) SELECT id FROM t1;
INSERT INTO t1 (id) SELECT id FROM t1;
INSERT INTO t1 (id) SELECT id FROM t1;
INSERT INTO t1 (id) SELECT id FROM t1;
INSERT INTO t1 SELECT id+1 FROM t1;
INSERT INTO t1 SELECT id+2 FROM t1;
INSERT INTO t1 SELECT id+4 FROM t1;
INSERT INTO t1 SELECT id+8 FROM t1;
INSERT INTO t1 SELECT id+16 FROM t1;
INSERT INTO t1 SELECT id+32 FROM t1;
INSERT INTO t1 SELECT id+64 FROM t1;
INSERT INTO t1 SELECT id+128 FROM t1;
INSERT INTO t1 SELECT id+256 FROM t1;
INSERT INTO t1 SELECT id+512 FROM t1;
INSERT INTO t1 SELECT id+1024 FROM t1;
INSERT INTO t1 SELECT id+2048 FROM t1;
INSERT INTO t1 SELECT id+4096 FROM t1;
INSERT INTO t1 SELECT id+8192 FROM t1;
INSERT INTO t2 SELECT id FROM t1 ORDER BY id*rand();
INSERT INTO t2 VALUE(NULL);
# With default tmp_table_size / max_heap_table_size
SELECT SQL_NO_CACHE count(DISTINCT id) sm FROM t2;
sm
16384
set @@tmp_table_size=1024*256;
# With reduced tmp_table_size
SELECT SQL_NO_CACHE count(DISTINCT id) sm FROM t2;
sm
16384
set @@tmp_table_size=@save_tmp_table_size;
SET @@max_heap_table_size=1024*256;
# With reduced max_heap_table_size
SELECT SQL_NO_CACHE count(DISTINCT id) sm FROM t2;
sm
16384
SET @@max_heap_table_size=@save_max_heap_table_size;
# Back to default tmp_table_size / max_heap_table_size
SELECT SQL_NO_CACHE count(DISTINCT id) sm FROM t2;
sm
16384
DROP TABLE t1,t2;
set storage_engine=@save_storage_engine;
|
