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mariadb/mysql-test/main/mrr_icp_extra.result
Alexander Barkov 4ced4898fd MDEV-32958 Unusable key notes do not get reported for some operations 
Enable unusable key notes for non-equality predicates:
   <, <=, =>, >, BETWEEN, IN, LIKE

Note, in some scenarios it displays duplicate notes, e.g.
for queries with ORDER BY:

  SELECT * FROM t1
  WHERE    indexed_string_column >= 10
  ORDER BY indexed_string_column
  LIMIT 5;

This should be tolarable. Getting rid of the diplicate note
completely would need a much more complex patch, which is
not desiable in 10.6.

Details:

- Changing RANGE_OPT_PARAM::note_unusable_keys from bool
  to a new data type Item_func::Bitmap, so the caller can
  choose with a better granuality which predicates
  should raise unusable key notes inside the range optimizer:
    a. all predicates (=, <=>, <, <=, =>, >, BETWEEN, IN, LIKE)
    b. all predicates except equality (=, <=>)
    c. none of the predicates

  "b." is needed because in some scenarios equality predicates (=, <=>)
  send unusable key notes at an earlier stage, before the range optimizer,
  during update_ref_and_keys(). Calling the range optimizer with
  "all predicates" would produce duplicate notes for = and <=> in such cases.

- Fixing get_quick_record_count() to call the range optimizer
  with "all predicates except equality" instead of "none of the predicates".
  Before this change the range optimizer suppressed all notes for
  non-equality predicates: <, <=, =>, >, BETWEEN, IN, LIKE.
  This actually fixes the reported problem.

- Fixing JOIN::make_range_rowid_filters() to call the range optimizer
  with "all predicates except equality" instead of "all predicates".
  Before this change the range optimizer produced duplicate notes
  for = and <=> during a rowid_filter optimization.

- Cleanup:
  Adding the op_collation argument to Field::raise_note_cannot_use_key_part()
  and displaying the operation collation rather than the argument collation
  in the unusable key note. This is important for operations with more than
  two arguments: BETWEEN and IN, e.g.:

    SELECT * FROM t1
    WHERE column_utf8mb3_general_ci
          BETWEEN 'a' AND 'b' COLLATE utf8mb3_unicode_ci;

    SELECT * FROM t1
    WHERE column_utf8mb3_general_ci
          IN ('a', 'b' COLLATE utf8mb3_unicode_ci);

    The note for 'a' now prints utf8mb3_unicode_ci as the collation.
    which is the collation of the entire operation:

      Cannot use key key1 part[0] for lookup:
      "`column_utf8mb3_general_ci`" of collation `utf8mb3_general_ci` >=
      "'a'" of collation `utf8mb3_unicode_ci`

    Before this change it printed the collation of 'a',
    so the note was confusing:

      Cannot use key key1 part[0] for lookup:
      "`column_utf8mb3_general_ci`" of collation `utf8mb3_general_ci` >=
      "'a'" of collation `utf8mb3_general_ci`"
2023-12-11 08:55:27 +04:00

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call mtr.add_suppression("Can't find record in .*");
set @mrr_icp_extra_tmp=@@optimizer_switch;
set optimizer_switch='mrr=on,mrr_sort_keys=on,index_condition_pushdown=on';
set optimizer_switch='rowid_filter=off';
SET NAMES latin1;
CREATE TABLE t1
(s1 char(10) COLLATE latin1_german1_ci,
s2 char(10) COLLATE latin1_swedish_ci,
KEY(s1),
KEY(s2));
INSERT INTO t1 VALUES ('a','a');
INSERT INTO t1 VALUES ('b','b');
INSERT INTO t1 VALUES ('c','c');
INSERT INTO t1 VALUES ('d','d');
INSERT INTO t1 VALUES ('e','e');
INSERT INTO t1 VALUES ('f','f');
INSERT INTO t1 VALUES ('g','g');
INSERT INTO t1 VALUES ('h','h');
INSERT INTO t1 VALUES ('i','i');
INSERT INTO t1 VALUES ('j','j');
EXPLAIN SELECT * FROM t1 WHERE s1='a';
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref s1 s1 11 const 1 Using index condition
EXPLAIN SELECT * FROM t1 WHERE s2='a';
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref s2 s2 11 const 1 Using index condition
EXPLAIN SELECT * FROM t1 WHERE s1='a' COLLATE latin1_german1_ci;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref s1 s1 11 const 1 Using index condition
EXPLAIN SELECT * FROM t1 WHERE s2='a' COLLATE latin1_german1_ci;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL s2 NULL NULL NULL 10 Using where
Warnings:
Note 1105 Cannot use key `s2` part[0] for lookup: `test`.`t1`.`s2` of collation `latin1_swedish_ci` = "'a' collate latin1_german1_ci" of collation `latin1_german1_ci`
EXPLAIN SELECT * FROM t1 WHERE s1 BETWEEN 'a' AND 'b' COLLATE latin1_german1_ci;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range s1 s1 11 NULL 2 Using index condition; Rowid-ordered scan
EXPLAIN SELECT * FROM t1 WHERE s2 BETWEEN 'a' AND 'b' COLLATE latin1_german1_ci;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL s2 NULL NULL NULL 10 Using where
Warnings:
Note 1105 Cannot use key `s2` part[0] for lookup: `test`.`t1`.`s2` of collation `latin1_swedish_ci` >= "'a'" of collation `latin1_german1_ci`
EXPLAIN SELECT * FROM t1 WHERE s1 IN ('a','b' COLLATE latin1_german1_ci);
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range s1 s1 11 NULL 2 Using index condition; Rowid-ordered scan
EXPLAIN SELECT * FROM t1 WHERE s2 IN ('a','b' COLLATE latin1_german1_ci);
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL s2 NULL NULL NULL 10 Using where
Warnings:
Note 1105 Cannot use key `s2` part[0] for lookup: `test`.`t1`.`s2` of collation `latin1_swedish_ci` = "'a'" of collation `latin1_german1_ci`
EXPLAIN SELECT * FROM t1 WHERE s1 LIKE 'a' COLLATE latin1_german1_ci;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range s1 s1 11 NULL 1 Using index condition; Rowid-ordered scan
EXPLAIN SELECT * FROM t1 WHERE s2 LIKE 'a' COLLATE latin1_german1_ci;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL s2 NULL NULL NULL 10 Using where
Warnings:
Note 1105 Cannot use key `s2` part[0] for lookup: `test`.`t1`.`s2` of collation `latin1_swedish_ci` like "'a' collate latin1_german1_ci" of collation `latin1_german1_ci`
DROP TABLE t1;
#
#
CREATE TABLE t2 (a varchar(32), b int(11), c float, d double,
UNIQUE KEY a (a,b,c), KEY b (b), KEY c (c));
CREATE TABLE t1 (a varchar(32), b char(3), UNIQUE KEY a (a,b), KEY b (b));
CREATE TABLE t3 (a varchar(32), b char(3), UNIQUE KEY a (a,b));
INSERT INTO t3 SELECT * FROM t1;
EXPLAIN
SELECT d FROM t1, t2
WHERE t2.b=14 AND t2.a=t1.a AND 5.1<t2.c AND t1.b='DE'
ORDER BY t2.c LIMIT 1;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE NULL NULL NULL NULL NULL NULL NULL Impossible WHERE noticed after reading const tables
SELECT d FROM t1, t2
WHERE t2.b=14 AND t2.a=t1.a AND 5.1<t2.c AND t1.b='DE'
ORDER BY t2.c LIMIT 1;
d
DROP TABLE t1,t2,t3;
#
#
create table t1(a int, b int, index(b));
insert into t1 values (2, 1), (1, 1), (4, NULL), (3, NULL), (6, 2), (5, 2);
insert into t1 values (2, 11), (1, 11), (4, 14), (3, 14), (6, 12), (5, 12);
explain select * from t1 where b=1 or b is null order by a;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref_or_null b b 5 const 4 Using index condition; Using filesort
select * from t1 where b=1 or b is null order by a;
a b
1 1
2 1
3 NULL
4 NULL
explain select * from t1 where b=2 or b is null order by a;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref_or_null b b 5 const 4 Using index condition; Using filesort
select * from t1 where b=2 or b is null order by a;
a b
3 NULL
4 NULL
5 2
6 2
drop table t1;
#
#
CREATE TABLE t1 (
FieldKey varchar(36) NOT NULL default '',
LongVal bigint(20) default NULL,
StringVal mediumtext,
KEY FieldKey (FieldKey),
KEY LongField (FieldKey,LongVal),
KEY StringField (FieldKey,StringVal(32))
);
INSERT INTO t1 VALUES ('0',3,'0'),('0',2,'1'),('0',1,'2'),('1',2,'1'),('1',1,'3'), ('1',0,'2'),('2',3,'0'),('2',2,'1'),('2',1,'2'),('2',3,'0'),('2',2,'1'),('2',1,'2'),('3',2,'1'),('3',1,'2'),('3','3','3');
EXPLAIN SELECT * FROM t1 IGNORE INDEX (LongField, StringField) WHERE FieldKey > '2' ORDER BY LongVal;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range FieldKey FieldKey 38 NULL 3 Using index condition; Rowid-ordered scan; Using filesort
EXPLAIN SELECT * FROM t1 IGNORE INDEX (FieldKey, LongField) WHERE FieldKey > '2' ORDER BY LongVal;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range StringField StringField 38 NULL 3 Using where; Using filesort
SELECT * FROM t1 WHERE FieldKey > '2' ORDER BY LongVal;
FieldKey LongVal StringVal
3 1 2
3 2 1
3 3 3
DROP TABLE t1;
#
#
CREATE TABLE t1 (a int not null, b int, c int, key(b), key(c), key(a,b), key(c,a));
INSERT into t1 values (0, null, 0), (0, null, 1), (0, null, 2), (0, null,3), (1,1,4);
create table t2 (a int not null, b int, c int, key(b), key(c), key(a));
INSERT into t2 values (1,1,1), (2,2,2);
optimize table t1;
Table Op Msg_type Msg_text
test.t1 optimize status OK
explain select * from t1 force index (a) where a=0 or a=2;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range a a 4 NULL 5 Using index condition; Rowid-ordered scan
select * from t1 force index (a) where a=0 or a=2;
a b c
0 NULL 0
0 NULL 1
0 NULL 2
0 NULL 3
drop table t1;
#
#
create table t1
(
pk1 int not null,
pk2 int not null,
key1 int not null,
key2 int not null,
pktail1ok int not null,
pktail2ok int not null,
pktail3bad int not null,
pktail4bad int not null,
pktail5bad int not null,
pk2copy int not null,
badkey int not null,
filler1 char (200),
filler2 char (200),
key (key1),
key (key2),
/* keys with tails from CPK members */
key (pktail1ok, pk1),
key (pktail2ok, pk1, pk2),
key (pktail3bad, pk2, pk1),
key (pktail4bad, pk1, pk2copy),
key (pktail5bad, pk1, pk2, pk2copy),
primary key (pk1, pk2)
);
explain select * from t1 where pk1 = 1 and pk2 < 80 and key1=0;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range PRIMARY,key1 PRIMARY 8 NULL 7 Using index condition; Using where; Rowid-ordered scan
select * from t1 where pk1 = 1 and pk2 < 80 and key1=0;
pk1 pk2 key1 key2 pktail1ok pktail2ok pktail3bad pktail4bad pktail5bad pk2copy badkey filler1 filler2
1 19 0 0 0 0 0 0 0 19 0 filler-data-19 filler2
1 18 0 0 0 0 0 0 0 18 0 filler-data-18 filler2
1 17 0 0 0 0 0 0 0 17 0 filler-data-17 filler2
1 16 0 0 0 0 0 0 0 16 0 filler-data-16 filler2
1 15 0 0 0 0 0 0 0 15 0 filler-data-15 filler2
1 14 0 0 0 0 0 0 0 14 0 filler-data-14 filler2
1 13 0 0 0 0 0 0 0 13 0 filler-data-13 filler2
1 12 0 0 0 0 0 0 0 12 0 filler-data-12 filler2
1 11 0 0 0 0 0 0 0 11 0 filler-data-11 filler2
1 10 0 0 0 0 0 0 0 10 0 filler-data-10 filler2
drop table t1;
#
#
CREATE TABLE t1 (
f1 int,
f4 varchar(32),
f5 int,
PRIMARY KEY (f1),
KEY (f4)
);
INSERT INTO t1 VALUES
(5,'H',1), (9,'g',0), (527,'i',0), (528,'y',1), (529,'S',6),
(530,'m',7), (531,'b',2), (532,'N',1), (533,'V',NULL), (534,'l',1),
(535,'M',0), (536,'w',1), (537,'j',5), (538,'l',0), (539,'n',2),
(540,'m',2), (541,'r',2), (542,'l',2), (543,'h',3),(544,'o',0),
(956,'h',0), (957,'g',0), (958,'W',5), (959,'s',3), (960,'w',0),
(961,'q',0), (962,'e',NULL), (963,'u',7), (964,'q',1), (965,'N',NULL),
(966,'e',0), (967,'t',3), (968,'e',6), (969,'f',NULL), (970,'j',0),
(971,'s',3), (972,'I',0), (973,'h',4), (974,'g',1), (975,'s',0),
(976,'r',3), (977,'x',1), (978,'v',8), (979,'j',NULL), (980,'z',7),
(981,'t',9), (982,'j',5), (983,'u',NULL), (984,'g',6), (985,'w',1),
(986,'h',1), (987,'v',0), (988,'v',0), (989,'c',2), (990,'b',7),
(991,'z',0), (992,'M',1), (993,'u',2), (994,'r',2), (995,'b',4),
(996,'A',2), (997,'u',0), (998,'a',0), (999,'j',2), (1,'I',2);
EXPLAIN
SELECT * FROM t1
WHERE (f1 < 535 OR f1 > 985) AND ( f4='r' OR f4 LIKE 'a%' ) ;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range PRIMARY,f4 f4 35 NULL 5 Using index condition; Using where; Rowid-ordered scan
SELECT * FROM t1
WHERE (f1 < 535 OR f1 > 985) AND ( f4='r' OR f4 LIKE 'a%' ) ;
f1 f4 f5
994 r 2
996 A 2
998 a 0
drop table t1;
#
#
drop table if exists t1,t2,t3;
--- Testing varchar ---
--- Testing varchar ---
create table t1 (v varchar(10), c char(10), t text);
insert into t1 values('+ ', '+ ', '+ ');
set @a=repeat(' ',20);
insert into t1 values (concat('+',@a),concat('+',@a),concat('+',@a));
Warnings:
Note 1265 Data truncated for column 'v' at row 1
select concat('*',v,'*',c,'*',t,'*') from t1;
concat('*',v,'*',c,'*',t,'*')
*+ *+*+ *
*+ *+*+ *
show create table t1;
Table Create Table
t1 CREATE TABLE `t1` (
`v` varchar(10) DEFAULT NULL,
`c` char(10) DEFAULT NULL,
`t` text DEFAULT NULL
) ENGINE=MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci
create table t2 like t1;
show create table t2;
Table Create Table
t2 CREATE TABLE `t2` (
`v` varchar(10) DEFAULT NULL,
`c` char(10) DEFAULT NULL,
`t` text DEFAULT NULL
) ENGINE=MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci
create table t3 select * from t1;
show create table t3;
Table Create Table
t3 CREATE TABLE `t3` (
`v` varchar(10) DEFAULT NULL,
`c` char(10) DEFAULT NULL,
`t` text DEFAULT NULL
) ENGINE=MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci
alter table t1 modify c varchar(10);
show create table t1;
Table Create Table
t1 CREATE TABLE `t1` (
`v` varchar(10) DEFAULT NULL,
`c` varchar(10) DEFAULT NULL,
`t` text DEFAULT NULL
) ENGINE=MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci
alter table t1 modify v char(10);
show create table t1;
Table Create Table
t1 CREATE TABLE `t1` (
`v` char(10) DEFAULT NULL,
`c` varchar(10) DEFAULT NULL,
`t` text DEFAULT NULL
) ENGINE=MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci
alter table t1 modify t varchar(10);
Warnings:
Note 1265 Data truncated for column 't' at row 2
show create table t1;
Table Create Table
t1 CREATE TABLE `t1` (
`v` char(10) DEFAULT NULL,
`c` varchar(10) DEFAULT NULL,
`t` varchar(10) DEFAULT NULL
) ENGINE=MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci
select concat('*',v,'*',c,'*',t,'*') from t1;
concat('*',v,'*',c,'*',t,'*')
*+*+*+ *
*+*+*+ *
drop table t1,t2,t3;
create table t1 (v varchar(10), c char(10), t text, key(v), key(c), key(t(10)));
show create table t1;
Table Create Table
t1 CREATE TABLE `t1` (
`v` varchar(10) DEFAULT NULL,
`c` char(10) DEFAULT NULL,
`t` text DEFAULT NULL,
KEY `v` (`v`),
KEY `c` (`c`),
KEY `t` (`t`(10))
) ENGINE=MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci
select count(*) from t1;
count(*)
270
insert into t1 values(concat('a',char(1)),concat('a',char(1)),concat('a',char(1)));
select count(*) from t1 where v='a';
count(*)
10
select count(*) from t1 where c='a';
count(*)
10
select count(*) from t1 where t='a';
count(*)
10
select count(*) from t1 where v='a ';
count(*)
10
select count(*) from t1 where c='a ';
count(*)
10
select count(*) from t1 where t='a ';
count(*)
10
select count(*) from t1 where v between 'a' and 'a ';
count(*)
10
select count(*) from t1 where v between 'a' and 'a ' and v between 'a ' and 'b\n';
count(*)
10
select count(*) from t1 where v like 'a%';
count(*)
11
select count(*) from t1 where c like 'a%';
count(*)
11
select count(*) from t1 where t like 'a%';
count(*)
11
select count(*) from t1 where v like 'a %';
count(*)
9
explain select count(*) from t1 where v='a ';
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref v v 13 const # Using where; Using index
explain select count(*) from t1 where c='a ';
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref c c 11 const # Using where; Using index
explain select count(*) from t1 where t='a ';
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref t t 13 const # Using where
explain select count(*) from t1 where v like 'a%';
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range v v 13 NULL # Using where; Using index
explain select count(*) from t1 where v between 'a' and 'a ';
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref v v 13 const # Using where; Using index
explain select count(*) from t1 where v between 'a' and 'a ' and v between 'a ' and 'b\n';
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref v v 13 const # Using where; Using index
alter table t1 add unique(v);
ERROR 23000: Duplicate entry '{ ' for key 'v_2'
show warnings;
Level Code Message
Error 1062 Duplicate entry 'a\0001' for key 'v_2'
alter table t1 add key(v);
Warnings:
Note 1831 Duplicate index `v_2`. This is deprecated and will be disallowed in a future release
select concat('*',v,'*',c,'*',t,'*') as qq from t1 where v='a';
qq
*a*a*a*
*a *a*a *
*a *a*a *
*a *a*a *
*a *a*a *
*a *a*a *
*a *a*a *
*a *a*a *
*a *a*a *
*a *a*a *
explain select * from t1 where v='a';
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref v,v_2 # 13 const # #
select v,count(*) from t1 group by v limit 10;
v count(*)
a 1
a 10
b 10
c 10
d 10
e 10
f 10
g 10
h 10
i 10
select v,count(t) from t1 group by v limit 10;
v count(t)
a 1
a 10
b 10
c 10
d 10
e 10
f 10
g 10
h 10
i 10
select v,count(c) from t1 group by v limit 10;
v count(c)
a 1
a 10
b 10
c 10
d 10
e 10
f 10
g 10
h 10
i 10
select sql_big_result v,count(t) from t1 group by v limit 10;
v count(t)
a 1
a 10
b 10
c 10
d 10
e 10
f 10
g 10
h 10
i 10
select sql_big_result v,count(c) from t1 group by v limit 10;
v count(c)
a 1
a 10
b 10
c 10
d 10
e 10
f 10
g 10
h 10
i 10
select c,count(*) from t1 group by c limit 10;
c count(*)
a 1
a 10
b 10
c 10
d 10
e 10
f 10
g 10
h 10
i 10
select c,count(t) from t1 group by c limit 10;
c count(t)
a 1
a 10
b 10
c 10
d 10
e 10
f 10
g 10
h 10
i 10
select sql_big_result c,count(t) from t1 group by c limit 10;
c count(t)
a 1
a 10
b 10
c 10
d 10
e 10
f 10
g 10
h 10
i 10
select t,count(*) from t1 group by t limit 10;
t count(*)
a 1
a 10
b 10
c 10
d 10
e 10
f 10
g 10
h 10
i 10
select t,count(t) from t1 group by t limit 10;
t count(t)
a 1
a 10
b 10
c 10
d 10
e 10
f 10
g 10
h 10
i 10
select sql_big_result t,count(t) from t1 group by t limit 10;
t count(t)
a 1
a 10
b 10
c 10
d 10
e 10
f 10
g 10
h 10
i 10
alter table t1 modify v varchar(300), drop key v, drop key v_2, add key v (v);
show create table t1;
Table Create Table
t1 CREATE TABLE `t1` (
`v` varchar(300) DEFAULT NULL,
`c` char(10) DEFAULT NULL,
`t` text DEFAULT NULL,
KEY `c` (`c`),
KEY `t` (`t`(10)),
KEY `v` (`v`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci
select count(*) from t1 where v='a';
count(*)
10
select count(*) from t1 where v='a ';
count(*)
10
select count(*) from t1 where v between 'a' and 'a ';
count(*)
10
select count(*) from t1 where v between 'a' and 'a ' and v between 'a ' and 'b\n';
count(*)
10
select count(*) from t1 where v like 'a%';
count(*)
11
select count(*) from t1 where v like 'a %';
count(*)
9
explain select count(*) from t1 where v='a ';
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref v v 303 const # Using where; Using index
explain select count(*) from t1 where v like 'a%';
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range v v 303 NULL # Using where; Using index
explain select count(*) from t1 where v between 'a' and 'a ';
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref v v 303 const # Using where; Using index
explain select count(*) from t1 where v between 'a' and 'a ' and v between 'a ' and 'b\n';
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref v v 303 const # Using where; Using index
explain select * from t1 where v='a';
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref v v 303 const # #
select v,count(*) from t1 group by v limit 10;
v count(*)
a 1
a 10
b 10
c 10
d 10
e 10
f 10
g 10
h 10
i 10
select v,count(t) from t1 group by v limit 10;
v count(t)
a 1
a 10
b 10
c 10
d 10
e 10
f 10
g 10
h 10
i 10
select sql_big_result v,count(t) from t1 group by v limit 10;
v count(t)
a 1
a 10
b 10
c 10
d 10
e 10
f 10
g 10
h 10
i 10
alter table t1 drop key v, add key v (v(30));
show create table t1;
Table Create Table
t1 CREATE TABLE `t1` (
`v` varchar(300) DEFAULT NULL,
`c` char(10) DEFAULT NULL,
`t` text DEFAULT NULL,
KEY `c` (`c`),
KEY `t` (`t`(10)),
KEY `v` (`v`(30))
) ENGINE=MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci
select count(*) from t1 where v='a';
count(*)
10
select count(*) from t1 where v='a ';
count(*)
10
select count(*) from t1 where v between 'a' and 'a ';
count(*)
10
select count(*) from t1 where v between 'a' and 'a ' and v between 'a ' and 'b\n';
count(*)
10
select count(*) from t1 where v like 'a%';
count(*)
11
select count(*) from t1 where v like 'a %';
count(*)
9
explain select count(*) from t1 where v='a ';
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref v v 33 const # Using where
explain select count(*) from t1 where v like 'a%';
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range v v 33 NULL # Using where
explain select count(*) from t1 where v between 'a' and 'a ';
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref v v 33 const # Using where
explain select count(*) from t1 where v between 'a' and 'a ' and v between 'a ' and 'b\n';
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref v v 33 const # Using where
explain select * from t1 where v='a';
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref v v 33 const # #
select v,count(*) from t1 group by v limit 10;
v count(*)
a 1
a 10
b 10
c 10
d 10
e 10
f 10
g 10
h 10
i 10
select v,count(t) from t1 group by v limit 10;
v count(t)
a 1
a 10
b 10
c 10
d 10
e 10
f 10
g 10
h 10
i 10
select sql_big_result v,count(t) from t1 group by v limit 10;
v count(t)
a 1
a 10
b 10
c 10
d 10
e 10
f 10
g 10
h 10
i 10
alter table t1 modify v varchar(600), drop key v, add key v (v);
show create table t1;
Table Create Table
t1 CREATE TABLE `t1` (
`v` varchar(600) DEFAULT NULL,
`c` char(10) DEFAULT NULL,
`t` text DEFAULT NULL,
KEY `c` (`c`),
KEY `t` (`t`(10)),
KEY `v` (`v`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci
select v,count(*) from t1 group by v limit 10;
v count(*)
a 1
a 10
b 10
c 10
d 10
e 10
f 10
g 10
h 10
i 10
select v,count(t) from t1 group by v limit 10;
v count(t)
a 1
a 10
b 10
c 10
d 10
e 10
f 10
g 10
h 10
i 10
select sql_big_result v,count(t) from t1 group by v limit 10;
v count(t)
a 1
a 10
b 10
c 10
d 10
e 10
f 10
g 10
h 10
i 10
drop table t1;
create table t1 (a char(10), unique (a));
insert into t1 values ('a ');
insert into t1 values ('a ');
ERROR 23000: Duplicate entry 'a' for key 'a'
alter table t1 modify a varchar(10);
insert into t1 values ('a '),('a '),('a '),('a ');
ERROR 23000: Duplicate entry 'a ' for key 'a'
insert into t1 values ('a ');
ERROR 23000: Duplicate entry 'a ' for key 'a'
insert into t1 values ('a ');
ERROR 23000: Duplicate entry 'a ' for key 'a'
insert into t1 values ('a ');
ERROR 23000: Duplicate entry 'a ' for key 'a'
update t1 set a='a ' where a like 'a%';
select concat(a,'.') from t1;
concat(a,'.')
a .
update t1 set a='abc ' where a like 'a ';
select concat(a,'.') from t1;
concat(a,'.')
a .
update t1 set a='a ' where a like 'a %';
select concat(a,'.') from t1;
concat(a,'.')
a .
update t1 set a='a ' where a like 'a ';
select concat(a,'.') from t1;
concat(a,'.')
a .
drop table t1;
create table t1 (v varchar(10), c char(10), t text, key(v(5)), key(c(5)), key(t(5)));
show create table t1;
Table Create Table
t1 CREATE TABLE `t1` (
`v` varchar(10) DEFAULT NULL,
`c` char(10) DEFAULT NULL,
`t` text DEFAULT NULL,
KEY `v` (`v`(5)),
KEY `c` (`c`(5)),
KEY `t` (`t`(5))
) ENGINE=MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci
drop table t1;
create table t1 (v char(10) character set utf8);
show create table t1;
Table Create Table
t1 CREATE TABLE `t1` (
`v` char(10) CHARACTER SET utf8mb3 COLLATE utf8mb3_general_ci DEFAULT NULL
) ENGINE=MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci
drop table t1;
create table t1 (v varchar(10), c char(10)) row_format=fixed;
show create table t1;
Table Create Table
t1 CREATE TABLE `t1` (
`v` varchar(10) DEFAULT NULL,
`c` char(10) DEFAULT NULL
) ENGINE=MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci ROW_FORMAT=FIXED
insert into t1 values('a','a'),('a ','a ');
select concat('*',v,'*',c,'*') from t1;
concat('*',v,'*',c,'*')
*a*a*
*a *a*
drop table t1;
create table t1 (v varchar(65530), key(v(10)));
insert into t1 values(repeat('a',65530));
select length(v) from t1 where v=repeat('a',65530);
length(v)
65530
drop table t1;
create table t1(a int, b varchar(12), key ba(b, a));
insert into t1 values (1, 'A'), (20, NULL);
explain select * from t1 where a=20 and b is null;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref ba ba 20 const,const 1 Using where; Using index
select * from t1 where a=20 and b is null;
a b
20 NULL
drop table t1;
#
#
drop database if exists world;
CREATE DATABASE world;
use world;
CREATE TABLE Country (
Code char(3) NOT NULL default '',
Name char(52) NOT NULL default '',
SurfaceArea float(10,2) NOT NULL default '0.00',
Population int(11) NOT NULL default '0',
Capital int(11) default NULL,
PRIMARY KEY (Code),
UNIQUE INDEX (Name)
);
CREATE TABLE City (
ID int(11) NOT NULL auto_increment,
Name char(35) NOT NULL default '',
Country char(3) NOT NULL default '',
Population int(11) NOT NULL default '0',
PRIMARY KEY (ID),
INDEX (Population),
INDEX (Country)
);
CREATE TABLE CountryLanguage (
Country char(3) NOT NULL default '',
Language char(30) NOT NULL default '',
Percentage float(3,1) NOT NULL default '0.0',
PRIMARY KEY (Country, Language),
INDEX (Percentage)
);
SELECT * FROM City
WHERE ((Name > 'Ca' AND Name < 'Cf') OR (Country > 'E' AND Country < 'F'))
AND (Population > 101000 AND Population < 102000);
ID Name Country Population
637 Mit Ghamr EGY 101801
707 Marbella ESP 101144
3792 Tartu EST 101246
4032 Cambridge USA 101355
explain
SELECT * FROM City
WHERE ((Name > 'Ca' AND Name < 'Cf') OR (Country > 'E' AND Country < 'F'))
AND (Population > 101000 AND Population < 102000);
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE City range Population,Country Population 4 NULL # Using index condition; Using where; Rowid-ordered scan
explain
SELECT * FROM City
WHERE (Name < 'Ac' AND (Country > 'A' AND Country < 'B')) OR
(Name BETWEEN 'P' AND 'Pb' AND (Population > 101000 AND Population < 110000));
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE City index_merge Population,Country Country,Population 3,4 NULL # Using sort_union(Country,Population); Using where
SELECT * FROM City
WHERE (Name < 'Ac' AND (Country > 'A' AND Country < 'B')) OR
(Name BETWEEN 'P' AND 'Pb' AND (Population > 101000 AND Population < 110000));
ID Name Country Population
65 Abu Dhabi ARE 398695
168 Pabna BGD 103277
189 Parakou BEN 103577
750 Paarl ZAF 105768
2865 Pak Pattan PAK 107800
SELECT * FROM City
WHERE Name LIKE 'M%' AND Population > 7000000;
ID Name Country Population
1024 Mumbai (Bombay) IND 10500000
3580 Moscow RUS 8389200
explain
SELECT * FROM City
WHERE Name LIKE 'M%' AND Population > 7000000;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE City range Population Population 4 NULL # Using index condition; Using where; Rowid-ordered scan
explain
SELECT * FROM City
WHERE Name BETWEEN 'G' AND 'K' AND Population > 500000 AND Country LIKE 'C%';
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE City range Population,Country # # NULL # Using index condition; Using where; Rowid-ordered scan
SELECT * FROM City
WHERE Name BETWEEN 'G' AND 'K' AND Population > 500000 AND Country LIKE 'C%';
ID Name Country Population
1895 Harbin CHN 4289800
1904 Jinan CHN 2278100
1905 Hangzhou CHN 2190500
1914 Guiyang CHN 1465200
1916 Hefei CHN 1369100
1923 Jilin CHN 1040000
1927 Hohhot CHN 916700
1928 Handan CHN 840000
1937 Huainan CHN 700000
1938 Jixi CHN 683885
1944 Jinzhou CHN 570000
1950 Hegang CHN 520000
explain
SELECT * FROM City
WHERE Name BETWEEN 'G' AND 'J' AND Population > 500000 AND Country LIKE 'C%';
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE City range Population,Country # # NULL # Using index condition; Using where; Rowid-ordered scan
SELECT * FROM City
WHERE Name BETWEEN 'G' AND 'J' AND Population > 500000 AND Country LIKE 'C%';
ID Name Country Population
1895 Harbin CHN 4289800
1905 Hangzhou CHN 2190500
1914 Guiyang CHN 1465200
1916 Hefei CHN 1369100
1927 Hohhot CHN 916700
1928 Handan CHN 840000
1937 Huainan CHN 700000
1950 Hegang CHN 520000
drop database world;
use test;
set @mrr_icp_extra_tmp=@@optimizer_switch;
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