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
|
drop table if exists t1,t2;
#
# MDEV-21958: Query having many NOT-IN clauses running forever
#
create table t2 (
pk int primary key,
key1 int,
col1 int,
key (key1, pk)
);
insert into t2 (pk, key1) values (1,1),(2,2),(3,3),(4,4),(5,5);
set @tmp_21958=@@optimizer_trace;
set optimizer_trace=1;
explain select * from t2 where key1 in (1,2,3) and pk not in (1,2,3);
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t2 range PRIMARY,key1 key1 5 NULL 3 Using index condition
# This should show only ranges in form "(1) <= (key1) <= (1)"
# ranges over "pk" should not be constructed.
select json_detailed(JSON_EXTRACT(trace, '$**.ranges'))
from information_schema.optimizer_trace;
json_detailed(JSON_EXTRACT(trace, '$**.ranges'))
[
[
"(1) <= (key1) <= (1)",
"(2) <= (key1) <= (2)",
"(3) <= (key1) <= (3)"
],
[
"(1) <= (key1) <= (1)",
"(2) <= (key1) <= (2)",
"(3) <= (key1) <= (3)"
]
]
set optimizer_trace=@tmp_21958;
drop table t2;
#
# MDEV-9750: Quick memory exhaustion with 'extended_keys=on'...
#
create table t1 (
kp1 int,
kp2 int,
kp3 int,
kp4 int,
key key1(kp1, kp2, kp3,kp4)
);
insert into t1 values (1,1,1,1),(2,2,2,2),(3,3,3,3);
analyze table t1;
Table Op Msg_type Msg_text
test.t1 analyze status Engine-independent statistics collected
test.t1 analyze status OK
show variables like 'optimizer_max_sel_arg_weight';
Variable_name Value
optimizer_max_sel_arg_weight 32000
set @tmp_9750=@@optimizer_trace;
set optimizer_trace=1;
explain select * from t1 where
kp1 in (1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20) and
kp2 in (1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20) and
kp3 in (1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20) and
kp4 in (1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20)
;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 index key1 key1 20 NULL 3 Using where; Using index
set @json= (select json_detailed(JSON_EXTRACT(trace, '$**.range_scan_alternatives'))
from information_schema.optimizer_trace);
# This will show 3-component ranges.
# The ranges were produced, but the optimizer has cut away kp4
# to keep the number of ranges at manageable level:
select left(@json, 500);
left(@json, 500)
[
[
{
"index": "key1",
"ranges":
[
"(1,1,1) <= (kp1,kp2,kp3) <= (1,1,1)",
"(1,1,2) <= (kp1,kp2,kp3) <= (1,1,2)",
"(1,1,3) <= (kp1,kp2,kp3) <= (1,1,3)",
"(1,1,4) <= (kp1,kp2,kp3) <= (1,1,4)",
"(1,1,5) <= (kp1,kp2,kp3) <= (1,1,5)",
"(1,1,6) <= (kp1,kp2,kp3) <= (1,1,6)",
"(1,1,7) <= (kp1,kp2,kp3) <= (1,1,7)",
"(1,1,8) <= (kp
## Repeat the above with low max_weight:
set @tmp9750_weight=@@optimizer_max_sel_arg_weight;
set optimizer_max_sel_arg_weight=20;
explain select * from t1 where
kp1 in (1,2,3,4,5,6,7,8,9,10) and
kp2 in (1,2,3,4,5,6,7,8,9,10) and
kp3 in (1,2,3,4,5,6,7,8,9,10) and
kp4 in (1,2,3,4,5,6,7,8,9,10)
;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 index key1 key1 20 NULL 3 Using where; Using index
set @trace= (select trace from information_schema.optimizer_trace);
set @json= json_detailed(json_extract(@trace, '$**.range_scan_alternatives'));
select left(@json, 500);
left(@json, 500)
[
[
{
"index": "key1",
"ranges":
[
"(1) <= (kp1) <= (1)",
"(2) <= (kp1) <= (2)",
"(3) <= (kp1) <= (3)",
"(4) <= (kp1) <= (4)",
"(5) <= (kp1) <= (5)",
"(6) <= (kp1) <= (6)",
"(7) <= (kp1) <= (7)",
"(8) <= (kp1) <= (8)",
"(9) <= (kp1) <= (9)",
"(10) <= (kp1) <= (10)"
],
set @json= json_detailed(json_extract(@trace, '$**.setup_range_conditions'));
select left(@json, 2500);
left(@json, 2500)
[
[
{
"sel_arg_weight_heuristic":
{
"key1_field": "kp1",
"key2_field": "kp2",
"key1_weight": 10,
"key2_weight": 10
}
},
{
"sel_arg_weight_heuristic":
{
"key1_field": "kp1",
"key2_field": "kp3",
"key1_weight": 10,
"key2_weight": 10
}
},
{
"sel_arg_weight_heuristic":
{
"key1_field": "kp1",
"key2_field": "kp4",
"key1_weight": 10,
"key2_weight": 10
}
}
]
]
## Repeat the above with a bit higher max_weight:
set optimizer_max_sel_arg_weight=120;
explain select * from t1 where
kp1 in (1,2,3,4,5,6,7,8,9,10) and
kp2 in (1,2,3,4,5,6,7,8,9,10) and
kp3 in (1,2,3,4,5,6,7,8,9,10) and
kp4 in (1,2,3,4,5,6,7,8,9,10)
;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 index key1 key1 20 NULL 3 Using where; Using index
set @json= (select json_detailed(JSON_EXTRACT(trace, '$**.range_scan_alternatives'))
from information_schema.optimizer_trace);
select left(@json, 1500);
left(@json, 1500)
[
[
{
"index": "key1",
"ranges":
[
"(1,1) <= (kp1,kp2) <= (1,1)",
"(1,2) <= (kp1,kp2) <= (1,2)",
"(1,3) <= (kp1,kp2) <= (1,3)",
"(1,4) <= (kp1,kp2) <= (1,4)",
"(1,5) <= (kp1,kp2) <= (1,5)",
"(1,6) <= (kp1,kp2) <= (1,6)",
"(1,7) <= (kp1,kp2) <= (1,7)",
"(1,8) <= (kp1,kp2) <= (1,8)",
"(1,9) <= (kp1,kp2) <= (1,9)",
"(1,10) <= (kp1,kp2) <= (1,10)",
"(2,1) <= (kp1,kp2) <= (2,1)",
"(2,2) <= (kp1,kp2) <= (2,2)",
"(2,3) <= (kp1,kp2) <= (2,3)",
"(2,4) <= (kp1,kp2) <= (2,4)",
"(2,5) <= (kp1,kp2) <= (2,5)",
"(2,6) <= (kp1,kp2) <= (2,6)",
"(2,7) <= (kp1,kp2) <= (2,7)",
"(2,8) <= (kp1,kp2) <= (2,8)",
"(2,9) <= (kp1,kp2) <= (2,9)",
"(2,10) <= (kp1,kp2) <= (2,10)",
"(3,1) <= (kp1,kp2) <= (3,1)",
"(3,2) <= (kp1,kp2) <= (3,2)",
"(3,3) <= (kp1,kp2) <= (3,3)",
"(3,4) <= (kp1,kp2) <= (3,4)",
"(3,5) <= (kp1,kp2) <= (3,5)",
"(3,6) <= (kp1,kp2) <= (3,6)",
"(3,7) <= (kp1,kp2) <= (3,7)",
"(3,8) <= (kp1,kp2) <= (3,8)",
"(3,9) <= (kp1,kp2) <= (3,9)",
"(3,10) <= (kp1,kp2) <= (3,10)",
set optimizer_max_sel_arg_weight= @tmp9750_weight;
set optimizer_trace=@tmp_9750;
drop table t1;
#
# MDEV-24739: Assertion `root->weight >= ...' failed in SEL_ARG::tree_delete
#
SELECT *
FROM mysql.help_relation
WHERE NOT (help_topic_id != 8 AND help_keyword_id != 0 OR help_keyword_id = 2 OR help_topic_id < 1900);
help_topic_id help_keyword_id
SELECT *
FROM mysql.help_relation ignore index (help_topic_id)
WHERE (help_topic_id = 8 OR help_keyword_id = 0) AND help_keyword_id != 2 AND help_topic_id >= 1900;
help_topic_id help_keyword_id
#
# MDEV-24953: 10.5.9 crashes with large IN() list
#
CREATE TABLE t1 (
notification_type_id smallint(4) unsigned NOT NULL DEFAULT 0,
item_id int(10) unsigned NOT NULL DEFAULT 0,
item_parent_id int(10) unsigned NOT NULL DEFAULT 0,
user_id int(10) unsigned NOT NULL DEFAULT 0,
PRIMARY KEY (notification_type_id,item_id,item_parent_id,user_id)
);
insert into t1 values (1,1,1,1), (2,2,2,2), (3,3,3,3);
insert into t1 select seq,seq,seq,seq from seq_10_to_30;
# Run crashing query
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range PRIMARY PRIMARY 2 NULL 5 Using where
drop table t1;
#
# MDEV-25069: Assertion `root->weight >= ...' failed in SEL_ARG::tree_delete #2
#
SELECT *
FROM mysql.help_relation
WHERE
(help_topic_id < '2' OR help_topic_id != 8 OR help_topic_id < 1) AND
help_keyword_id = help_topic_id;
help_topic_id help_keyword_id
#
# MDEV-29242: Assertion `computed_weight == weight' failed SEL_ARG::verify_weight
#
CREATE TABLE t1 (id INT, KEY (id));
INSERT INTO t1 VALUES (1),(5);
SELECT id FROM t1 WHERE id IS NULL OR id NOT BETWEEN 1 AND 4;
id
5
DROP TABLE t1;
#
# MDEV-34620: Many index_merge variants made and discarded for a big OR
#
CREATE TABLE t1 (
a1 int NOT NULL,
a2 int NOT NULL,
filler char(100),
KEY key1 (a1,a2),
KEY key2 (a2,a1)
);
insert into t1 (a1,a2) values (1,1),(2,2),(3,3);
set @query= concat(
"explain select * from t1 where\n",
(select
group_concat(concat("a1=", seq, " and a2=", seq, " ") separator "\nor " )
from seq_1_to_30)
);
set optimizer_trace=1;
prepare s from @query;
execute s;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL key1,key2 NULL NULL NULL 3 Using where
set @trace=json_extract((select trace from information_schema.optimizer_trace), '$**.range_analysis');
# Observe that "key1" is a a part of several index_merge_union:
select json_pretty(json_search(@trace, 'all', 'key1'));
json_pretty(json_search(@trace, 'all', 'key1'))
[
"$[0].potential_range_indexes[0].index",
"$[0].analyzing_range_alternatives.range_scan_alternatives[0].index",
"$[0].analyzing_range_alternatives.analyzing_index_merge_union[0].indexes_to_merge[0].range_scan_alternatives[0].index",
"$[0].analyzing_range_alternatives.analyzing_index_merge_union[0].indexes_to_merge[1].range_scan_alternatives[0].index",
"$[0].analyzing_range_alternatives.analyzing_index_merge_union[1].indexes_to_merge[0].range_scan_alternatives[0].index",
"$[0].analyzing_range_alternatives.analyzing_index_merge_union[1].indexes_to_merge[1].range_scan_alternatives[0].index",
"$[0].analyzing_range_alternatives.analyzing_index_merge_union[1].indexes_to_merge[2].range_scan_alternatives[0].index",
"$[0].analyzing_range_alternatives.analyzing_index_merge_union[2].indexes_to_merge[0].range_scan_alternatives[0].index",
"$[0].analyzing_range_alternatives.analyzing_index_merge_union[2].indexes_to_merge[1].range_scan_alternatives[0].index"
]
#
# Now, same as above but for a long IN-list
#
set @query= concat(
"explain select * from t1 where\n",
(select
group_concat(concat("a1=", seq, " and a2=", seq, " ") separator "\nor " )
from seq_1_to_120)
);
set optimizer_trace=1;
prepare s from @query;
execute s;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL key1,key2 NULL NULL NULL 3 Using where
set @trace=json_extract((select trace from information_schema.optimizer_trace), '$**.range_analysis');
# Observe that there are NO index_merge_union candidates. Only one potential range scan:
select json_pretty(json_search(@trace, 'all', 'key1'));
json_pretty(json_search(@trace, 'all', 'key1'))
[
"$[0].potential_range_indexes[0].index",
"$[0].analyzing_range_alternatives.range_scan_alternatives[0].index"
]
drop table t1;
|
