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
|
drop table if exists t0, t1;
create table t0 (a int) engine=myisam;
insert into t0 values (1),(2),(3),(4),(5),(6),(7),(8);
#
# Tests for single-table DELETE
#
explain select * from t0 where a=3;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t0 ALL NULL NULL NULL NULL 8 Using where
explain delete from t0 where a=3;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t0 ALL NULL NULL NULL NULL 8 Using where
# DELETE without WHERE is a special case:
explain delete from t0;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE NULL NULL NULL NULL NULL NULL 8 Deleting all rows
create table t1 (a int, b int, filler char(100), key(a), key(b));
insert into t1
select A.a+10*B.a + 10*C.a, A.a+10*B.a + 10*C.a, 'filler'
from t0 A, t0 B, t0 C;
# This should use an index, possible_keys=NULL because there is no WHERE
explain delete from t1 order by a limit 2;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 index NULL a 5 NULL 2
# This should use range, possible_keys={a,b}
explain delete from t1 where a<20 and b < 10;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range a,b a 5 NULL 1 Using where
# This should use ALL + filesort
explain delete from t1 order by a+1 limit 2;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 512 Using filesort
# This should use range + using filesort
explain delete from t1 where a<20 order by b limit 2;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range a a 5 NULL 1 Using where; Using filesort
# Try some subqueries:
explain delete from t1 where a < (select max(a) from t0);
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1 range a a 5 NULL 1 Using where
2 SUBQUERY t0 ALL NULL NULL NULL NULL 8
explain delete from t1 where a < (select max(a) from t0 where a < t1.b);
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1 ALL NULL NULL NULL NULL 512 Using where
2 DEPENDENT SUBQUERY t0 ALL NULL NULL NULL NULL 8 Using where
#
# Tests for multi-table DELETE
#
explain delete t1 from t0, t1 where t0.a = t1.a;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t0 ALL NULL NULL NULL NULL 8 Using where
1 SIMPLE t1 ref a a 5 test.t0.a 4
drop table t0, t1;
# ###################################################################
# ## EXPLAIN UPDATE tests
# ###################################################################
create table t0 (a int) engine=myisam;
insert into t0 values (1),(2),(3),(4),(5),(6),(7),(8);
explain update t0 set a=3 where a=4;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t0 ALL NULL NULL NULL NULL 8 Using where
create table t1 (a int, b int, filler char(100), key(a), key(b));
insert into t1
select A.a+10*B.a + 10*C.a, A.a+10*B.a + 10*C.a, 'filler'
from t0 A, t0 B, t0 C;
explain update t1 set a=a+1 where 3>4;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE NULL NULL NULL NULL NULL NULL NULL Impossible WHERE
explain update t1 set a=a+1 where a=3 and a=4;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE NULL NULL NULL NULL NULL NULL NULL Impossible WHERE
# This should use an index, possible_keys=NULL because there is no WHERE
explain update t1 set a=a+1 order by a limit 2;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 512 Using filesort
# This should use range, possible_keys={a,b}
explain update t1 set filler='fooo' where a<20 and b < 10;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range a,b a 5 NULL 1 Using where
# This should use ALL + filesort
explain update t1 set filler='fooo' order by a+1 limit 2;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 512 Using filesort
# This should use range + using filesort
explain update t1 set filler='fooo' where a<20 order by b limit 2;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range a a 5 NULL 1 Using where; Using filesort
# Try some subqueries:
explain update t1 set filler='fooo' where a < (select max(a) from t0);
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1 range a a 5 NULL 1 Using where
2 SUBQUERY t0 ALL NULL NULL NULL NULL 8
explain update t1 set filler='fooo' where a < (select max(a) from t0 where a < t1.b);
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1 ALL NULL NULL NULL NULL 512 Using where
2 DEPENDENT SUBQUERY t0 ALL NULL NULL NULL NULL 8 Using where
#
# Tests for multi-table UPDATE
#
explain update t0, t1 set t1.a=t1.a+1 where t0.a = t1.a;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t0 ALL NULL NULL NULL NULL 8 Using where
1 SIMPLE t1 ref a a 5 test.t0.a 4
drop table t0, t1;
#
# Try DELETE ... RETURNING ...
#
create table t0 (a int);
insert into t0 values (1),(2),(3),(4);
explain delete from t0 where a=1 returning a;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t0 ALL NULL NULL NULL NULL 4 Using where
explain delete from t0 returning a;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t0 ALL NULL NULL NULL NULL 4
drop table t0;
#
# MDEV-5070 - EXPLAIN INSERT ... SELECT crashes on 10.0-base-explain-slowquerylog
#
create table t0 (a int);
insert into t0 values (1),(2),(3),(4),(5),(6),(7),(8);
create table t1 (a int);
explain insert into t1 select * from t0;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t0 ALL NULL NULL NULL NULL 8
explain replace into t1 select * from t0;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t0 ALL NULL NULL NULL NULL 8
drop table t0, t1;
#
# MDEV-5067: Valgrind warnings (Invalid read) in QPF_table_access::print_explain
#
CREATE TABLE t1 (i INT) ENGINE=MyISAM;
INSERT INTO t1 VALUES (7),(0),(9);
SELECT * FROM t1 INNER JOIN ( SELECT DISTINCT * FROM t1 ) AS sq ON (sq.i = t1.i);
i i
7 7
0 0
9 9
DROP TABLE t1;
#
# MDEV-5093, MDEV-5094: EXPLAIN PARTITIONS and EXPLAIN EXTENDED do not
# work for EXPLAIN UPDATE.
#
create table t1 (i int);
explain partitions update t1 set i = 3;
id select_type table partitions type possible_keys key key_len ref rows Extra
1 SIMPLE t1 NULL ALL NULL NULL NULL NULL 0
create table t2 (a int, b int) partition by hash(a) partitions 5;
insert into t2 values (0,0),(1,1),(2,2),(3,3),(4,4);
explain partitions update t2 set b=3 where a in (3,4);
id select_type table partitions type possible_keys key key_len ref rows Extra
1 SIMPLE t2 p3,p4 ALL NULL NULL NULL NULL 2 Using where
explain partitions delete from t2 where a in (3,4);
id select_type table partitions type possible_keys key key_len ref rows Extra
1 SIMPLE t2 p3,p4 ALL NULL NULL NULL NULL 2 Using where
explain extended update t2 set b=3 where a in (3,4);
id select_type table type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t2 ALL NULL NULL NULL NULL 2 100.00 Using where
explain extended delete from t2 where a in (3,4);
id select_type table type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t2 ALL NULL NULL NULL NULL 2 100.00 Using where
drop table t1,t2;
#
# Check the special case where partition pruning removed all partitions
#
create table t1 (a int, b int)
partition by range (a) (
partition p0 values less than (10),
partition p1 values less than (20),
partition p2 values less than (30)
);
insert into t1 values (9,9), (19,19), (29,29);
explain partitions select * from t1 where a in (32,33);
id select_type table partitions type possible_keys key key_len ref rows Extra
1 SIMPLE NULL NULL NULL NULL NULL NULL NULL NULL Impossible WHERE noticed after reading const tables
explain partitions delete from t1 where a in (32,33);
id select_type table partitions type possible_keys key key_len ref rows Extra
1 SIMPLE NULL NULL NULL NULL NULL NULL NULL NULL No matching rows after partition pruning
explain partitions update t1 set b=12345 where a in (32,33);
id select_type table partitions type possible_keys key key_len ref rows Extra
1 SIMPLE NULL NULL NULL NULL NULL NULL NULL NULL No matching rows after partition pruning
drop table t1;
#
# Tests for EXPLAIN INSERT ... VALUES
#
create table t1 (a int, key(a));
explain insert into t1 values (1),(2),(3);
id select_type table type possible_keys key key_len ref rows Extra
1 INSERT t1 ALL NULL NULL NULL NULL NULL NULL
insert into t1 values (1),(2),(3);
create table t2 (a int, b int);
explain insert into t2 values
(10, 1+(select max(a) from t1)),
(11, 1+(select max(a+1) from t1));
id select_type table type possible_keys key key_len ref rows Extra
1 INSERT t2 ALL NULL NULL NULL NULL NULL NULL
3 SUBQUERY t1 index NULL a 5 NULL 3 Using index
2 SUBQUERY NULL NULL NULL NULL NULL NULL NULL Select tables optimized away
drop table t1,t2;
#
# MDEV-5122: "Commands out of sync", "Malformed packet" or client hang up on unique key violation
#
drop table if exists t1;
Warnings:
Note 1051 Unknown table 'test.t1'
drop function if exists f1;
create table t1 (a int, unique(a));
create function f1(x int)
returns int
begin
insert into t1 values(x),(x);
return 10;
end|
select f1(100);
ERROR 23000: Duplicate entry '100' for key 'a'
select 'OK';
OK
OK
drop function f1;
drop table t1;
#
# MDEV-7038: Assertion `status_var.memory_used == 0' failed in THD::~THD()
# on disconnect after executing EXPLAIN for multi-table UPDATE
#
CREATE TABLE t1 (a INT);
CREATE VIEW v1 AS SELECT * FROM t1;
INSERT INTO t1 VALUES (1),(2);
EXPLAIN UPDATE v1, mysql.user SET v1.a = v1.a + 1;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 2
1 SIMPLE global_priv index NULL PRIMARY 420 NULL 4 Using index
DROP TABLE t1;
DROP VIEW v1;
#
# MDEV-8299: MyISAM or Aria table gets corrupted after EXPLAIN INSERT and INSERT
#
CREATE TABLE t1 (pk INT NOT NULL AUTO_INCREMENT PRIMARY KEY, i INT, KEY(i)) ENGINE=MyISAM;
INSERT INTO t1 (i) VALUES (100),(200);
CREATE TABLE t2 (j INT) ENGINE=MyISAM;
INSERT INTO t2 VALUES (10),(20);
EXPLAIN INSERT INTO t1 (i) SELECT j FROM t2;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t2 ALL NULL NULL NULL NULL 2
INSERT INTO t1 (i) VALUES (300);
CHECK TABLE t1;
Table Op Msg_type Msg_text
test.t1 check status OK
DROP TABLE t1, t2;
#
# MDEV-8321: Assertion `! is_set()' failed in Diagnostics_area::set_eof_status on EXPLAIN INSERT ... UNION
#
CREATE TABLE t1 (a INT);
CREATE TABLE t2 (b INT);
CREATE TABLE t3 (c INT);
INSERT INTO t1 VALUES (1),(2);
INSERT INTO t2 VALUES (3),(4);
INSERT INTO t3 VALUES (5),(6);
EXPLAIN INSERT INTO t1 SELECT * FROM t2 UNION SELECT * FROM t3;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t2 ALL NULL NULL NULL NULL 2
2 UNION t3 ALL NULL NULL NULL NULL 2
NULL UNION RESULT <union1,2> ALL NULL NULL NULL NULL NULL
drop table t1,t2,t3;
#
# MDEV-6223: Assertion `! is_set()' fails in Diagnostics_area::set_eof_status on EXPLAIN INSERT executed as a PS
#
CREATE TABLE t1 (a INT) ENGINE = MyISAM;
CREATE TABLE t2 (b INT) ENGINE = MyISAM;
INSERT INTO t2 VALUES (1),(2);
PREPARE stmt FROM 'EXPLAIN INSERT INTO t1 SELECT * FROM t2';
EXECUTE stmt;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t2 ALL NULL NULL NULL NULL 2
drop table t1,t2;
|
