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
|
-- echo
-- echo /* A. Subqueries in the SELECT clause. */
explain
select a1, a1 in (select b1 from t2 where b1 > '0') from t1;
select a1, a1 in (select b1 from t2 where b1 > '0') from t1;
-- echo
explain
select a1, a2, (a1, a2) in (select b1, b2 from t2 where b1 > '0') from t1;
select a1, a2, (a1, a2) in (select b1, b2 from t2 where b1 > '0') from t1;
-- echo
explain
select a1, a2, (a1, a2) in (select b1, b2 from t2 where b1 > '0' and b1 < '9') from t1;
select a1, a2, (a1, a2) in (select b1, b2 from t2 where b1 > '0' and b1 < '9') from t1;
-- echo
-- echo /*
-- echo B. "Natural" examples of subqueries without grouping that
-- echo cannot be flattened into semijoin.
-- echo */
explain
select a1 from t1 where a1 in (select b2 from t2) or a2 < '9';
select a1 from t1 where a1 in (select b2 from t2) or a2 < '9';
-- echo
explain
select a1, a2 from t1 where (a1, a2) in (select b1, b2 from t2 where b1 > '0') or a2 < '9';
select a1, a2 from t1 where (a1, a2) in (select b1, b2 from t2 where b1 > '0') or a2 < '9';
-- echo UNION subqueries are currently limited to only use IN-TO-EXISTS.
explain
select a2 from t1 where a2 in (select b2 from t2 UNION select b3 from t2 as t3);
select a2 from t1 where a2 in (select b2 from t2 UNION select b3 from t2 as t3);
-- echo
explain
select a1 from t1 where a1 = '1 - 02' and a1 in (select max(b1) from t2 where b2 = '2 - 02');
select a1 from t1 where a1 = '1 - 02' and a1 in (select max(b1) from t2 where b2 = '2 - 02');
-- echo
explain
select a1, a2 from t1 where (a1, a2) in (select b1, b2 from t2 order by b3);
select a1, a2 from t1 where (a1, a2) in (select b1, b2 from t2 order by b3);
-- echo
-- echo /* C. Subqueries in the WHERE clause with GROUP BY. */
explain
select * from t1 where a1 in (select b1 from t2 where b1 > '0' group by b1);
select * from t1 where a1 in (select b1 from t2 where b1 > '0' group by b1);
-- echo
explain
select * from t1 where (a1, a2) in (select b1, b2 from t2 where b1 > '0' group by b1, b2);
select * from t1 where (a1, a2) in (select b1, b2 from t2 where b1 > '0' group by b1, b2);
-- echo
explain
select * from t1 where (a1, a2) in (select b1, b2 from t2 where b1 > '0' group by b1, b2 having b2 < '2 - 04');
select * from t1 where (a1, a2) in (select b1, b2 from t2 where b1 > '0' group by b1, b2 having b2 < '2 - 04');
-- echo
explain
select * from t1 where (a1, a2, a3) in (select b1, b2, b3 from t2 group by b1, b2, b3);
select * from t1 where (a1, a2, a3) in (select b1, b2, b3 from t2 group by b1, b2, b3);
-- echo
explain
select * from t1 where (a1, a2, a3) in (select b1, b2, b3 from t2 where b3 = '3 - 02' group by b1, b2);
select * from t1 where (a1, a2, a3) in (select b1, b2, b3 from t2 where b3 = '3 - 02' group by b1, b2);
-- echo
explain
select * from t1 where (a1,a2,a3) in (select b1,b2,b3 from t2 where b1 = '1 - 01' group by b1,b2,b3);
select * from t1 where (a1,a2,a3) in (select b1,b2,b3 from t2 where b1 = '1 - 01' group by b1,b2,b3);
-- echo
-- echo /*
-- echo D. Subqueries for which materialization is not possible, and the
-- echo optimizer reverts to in-to-exists.
-- echo */
# The first two cases are rejected during the prepare phase by the procedure
# subquery_types_allow_materialization().
explain
select left(a1,7), left(a2,7) from t1_1024 where a1 in (select b1 from t2_1024 where b1 > '0') or a2 < '9';
select left(a1,7), left(a2,7) from t1_1024 where a1 in (select b1 from t2_1024 where b1 > '0') or a2 < '9';
explain
select left(a1,7), left(a2,7) from t1_1024 where (a1,a2) in (select b1, b2 from t2_1024 where b1 > '0') or a2 < '9';
select left(a1,7), left(a2,7) from t1_1024 where (a1,a2) in (select b1, b2 from t2_1024 where b1 > '0') or a2 < '9';
-- echo
# The following two subqueries return the result of a string function with a
# blob argument, where the return type may be != blob. These are rejected during
# cost-based optimization when attempting to create a temporary table.
explain
select left(a1,7), left(a2,7) from t1_1024 where a1 in (select substring(b1,1,1024) from t2_1024 where b1 > '0') or a2 < '9';
select left(a1,7), left(a2,7) from t1_1024 where a1 in (select substring(b1,1,1024) from t2_1024 where b1 > '0') or a2 < '9';
explain
select left(a1,7), left(a2,7) from t1_1024 where (a1,a2) in (select substring(b1,1,1024), substring(b2,1,1024) from t2_1024 where b1 > '0') or a2 < '9';
select left(a1,7), left(a2,7) from t1_1024 where (a1,a2) in (select substring(b1,1,1024), substring(b2,1,1024) from t2_1024 where b1 > '0') or a2 < '9';
-- echo
-- echo
-- echo /* E. Edge cases. */
-- echo
-- echo /* E.1 Both materialization and in_to_exists cannot be off. */
set @save_optimizer_switch=@@optimizer_switch;
set @@optimizer_switch = 'materialization=off,in_to_exists=off';
--error ER_ILLEGAL_SUBQUERY_OPTIMIZER_SWITCHES
select * from t1 where a1 in (select b1 from t2 where b1 > '0' group by b1);
set @@optimizer_switch = @save_optimizer_switch;
-- echo /* E.2 Outer query without tables, always uses IN-TO-EXISTS. */
explain
select '1 - 03' in (select b1 from t2 where b1 > '0');
select '1 - 03' in (select b1 from t2 where b1 > '0');
-- echo /* E.3 Subqueries without tables. */
explain
select a1 from t1 where a1 in (select '1 - 03') or a2 < '9';
select a1 from t1 where a1 in (select '1 - 03') or a2 < '9';
-- echo UNION subqueries are currently limited to only use IN-TO-EXISTS.
explain
select a1 from t1 where a1 in (select '1 - 03' UNION select '1 - 02');
select a1 from t1 where a1 in (select '1 - 03' UNION select '1 - 02');
-- echo /* E.4 optimize_cond detects FALSE where/having clause. */
explain
select a1 from t1 where a1 in (select b1 from t2 where b1 = b2 and b2 = '1 - 03' and b1 = '1 - 02' ) or a2 < '9';
select a1 from t1 where a1 in (select b1 from t2 where b1 = b2 and b2 = '1 - 03' and b1 = '1 - 02' ) or a2 < '9';
-- echo /* E.5 opt_sum_query detects no matching min/max row or substitutes MIN/MAX with a const. */
-- echo TODO this test produces wrong result due to missing logic to handle the case
-- echo when JOIN::optimize detects an empty subquery result.
explain
select a1 from t1 where a1 in (select max(b1) from t2);
select a1 from t1 where a1 in (select max(b1) from t2);
-- echo
explain
select a1 from t1 where a1 in (select max(b1) from t2 where b1 = '7 - 02');
select a1 from t1 where a1 in (select max(b1) from t2 where b1 = '7 - 02');
-- echo /* E.6 make_join_select detects impossible WHERE. *
-- echo TODO
-- echo /* E.7 constant optimization detects "no matching row in const table". */
-- echo TODO
-- echo /* E.8 Impossible WHERE noticed after reading const tables. */
explain
select '1 - 03' in (select b1 from t2 where b1 > '0' and b1 < '0');
select '1 - 03' in (select b1 from t2 where b1 > '0' and b1 < '0');
-- echo
-- echo /* F. UPDATE/DELETE with subqueries. */
-- echo
-- echo TODO
-- echo
|
