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|
drop table if exists t1,t2,t3;
create temporary table t1 (a int not null,b int not null, primary key (a)) engine=MEMORY comment="testing heaps";
insert into t1 values(1,1),(2,2),(3,3),(4,4);
delete from t1 where a=1 or a=0;
show table status like "t1";
Session Schema Name Type Engine Version Rows Avg_row_length Table_size Auto_increment
# test t1 TEMPORARY MEMORY # # # # #
show keys from t1;
Table Unique Key_name Seq_in_index Column_name
t1 YES PRIMARY 1 a
select * from t1;
a b
2 2
3 3
4 4
select * from t1 where a=4;
a b
4 4
update t1 set b=5 where a=4;
update t1 set b=b+1 where a>=3;
replace t1 values (3,3);
select * from t1;
a b
2 2
3 3
4 6
alter table t1 add c int DEFAULT 42 not null, add key (c,a);
drop table t1;
create temporary table t1 (a int not null,b int not null, primary key (a)) engine=memory comment="testing heaps";
insert into t1 values(1,1),(2,2),(3,3),(4,4);
delete from t1 where a > 0;
select * from t1;
a b
drop table t1;
create temporary table t1 (a int not null,b int not null, primary key (a)) engine=MEMORY comment="testing heaps";
insert into t1 values(1,1),(2,2),(3,3),(4,4);
alter table t1 modify a int not null auto_increment, engine=innodb, comment="new innodb table";
show table status like "t1";
Session Schema Name Type Engine Version Rows Avg_row_length Table_size Auto_increment
# test t1 TEMPORARY InnoDB # # # # #
select * from t1;
a b
1 1
2 2
3 3
4 4
drop table t1;
create temporary table t1 (a int not null) engine=MEMORY;
insert into t1 values (869751),(736494),(226312),(802616),(728912);
select * from t1 where a > 736494;
a
869751
802616
alter table t1 add unique uniq_id(a);
select * from t1 where a > 736494;
a
869751
802616
select * from t1 where a = 736494;
a
736494
select * from t1 where a=869751 or a=736494;
a
736494
869751
select * from t1 where a in (869751,736494,226312,802616);
a
226312
736494
802616
869751
create temporary table t2 SELECT * FROM t1;
explain select * from t2 where a in (869751,736494,226312,802616);
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t2 ALL NULL NULL NULL NULL 5 Using where
drop table t1,t2;
create temporary table t1 (x int not null, y int not null, key x (x), unique y (y))
engine=MEMORY;
insert into t1 values (1,1),(2,2),(1,3),(2,4),(2,5),(2,6);
select * from t1 where x=1;
x y
1 3
1 1
select * from t1,t1 as t2 where t1.x=t2.y;
ERROR HY000: Can't reopen table: 't1'
explain select * from t1,t1 as t2 where t1.x=t2.y;
ERROR HY000: Can't reopen table: 't1'
drop table t1;
create temporary table t1 (a int) engine=MEMORY;
insert into t1 values(1);
select max(a) from t1;
max(a)
1
drop table t1;
CREATE TEMPORARY TABLE t1 ( a int not null default 0, b int not null default 0, key(a), key(b) ) ENGINE=MEMORY;
insert into t1 values(1,1),(1,2),(2,3),(1,3),(1,4),(1,5),(1,6);
select * from t1 where a=1;
a b
1 6
1 5
1 4
1 3
1 2
1 1
insert into t1 values(1,1),(1,2),(2,3),(1,3),(1,4),(1,5),(1,6);
select * from t1 where a=1;
a b
1 6
1 5
1 4
1 3
1 2
1 1
1 6
1 5
1 4
1 3
1 2
1 1
drop table t1;
create temporary table t1 (id int not null, primary key (id)) engine=MEMORY;
insert into t1 values(1);
select max(id) from t1;
max(id)
1
insert into t1 values(2);
select max(id) from t1;
max(id)
2
replace into t1 values(1);
drop table t1;
create temporary table t1 (n int) engine=MEMORY;
drop table t1;
create temporary table t1 (n int) engine=MEMORY;
drop table if exists t1;
CREATE TEMPORARY table t1(f1 int not null,f2 char(20) not
null,index(f2)) engine=MEMORY;
INSERT into t1 set f1=12,f2="bill";
INSERT into t1 set f1=13,f2="bill";
INSERT into t1 set f1=14,f2="bill";
INSERT into t1 set f1=15,f2="bill";
INSERT into t1 set f1=16,f2="ted";
INSERT into t1 set f1=12,f2="ted";
INSERT into t1 set f1=12,f2="ted";
INSERT into t1 set f1=12,f2="ted";
INSERT into t1 set f1=12,f2="ted";
delete from t1 where f2="bill";
select * from t1;
f1 f2
16 ted
12 ted
12 ted
12 ted
12 ted
drop table t1;
create temporary table t1 (btn char(10) not null, key(btn)) engine=MEMORY;
insert into t1 values ("hello"),("hello"),("hello"),("hello"),("hello"),("a"),("b"),("c"),("d"),("e"),("f"),("g"),("h"),("i");
explain select * from t1 where btn like "q%";
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL btn NULL NULL NULL 14 Using where
select * from t1 where btn like "q%";
btn
alter table t1 add column new_col char(1) DEFAULT "Y" not null, add key (btn,new_col), drop key btn;
update t1 set new_col=left(btn,1);
explain select * from t1 where btn="a";
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL btn NULL NULL NULL 14 Using where
explain select * from t1 where btn="a" and new_col="a";
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref btn btn 48 const,const 2 Using where
drop table t1;
CREATE TEMPORARY TABLE t1 (
a int default NULL,
b int default NULL,
KEY a (a),
UNIQUE b (b)
) engine=MEMORY;
INSERT INTO t1 VALUES (NULL,99),(99,NULL),(1,1),(2,2),(1,3);
SELECT * FROM t1 WHERE a=NULL;
a b
explain SELECT * FROM t1 WHERE a IS NULL;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref a a 5 const 2 Using where
SELECT * FROM t1 WHERE a<=>NULL;
a b
NULL 99
SELECT * FROM t1 WHERE b=NULL;
a b
explain SELECT * FROM t1 WHERE b IS NULL;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref b b 5 const 1 Using where
SELECT * FROM t1 WHERE b<=>NULL;
a b
99 NULL
INSERT INTO t1 VALUES (1,3);
ERROR 23000: Duplicate entry '3' for key 'b'
DROP TABLE t1;
CREATE TEMPORARY TABLE t1 (
a int default NULL,
key a (a)
) ENGINE=MEMORY;
INSERT INTO t1 VALUES (10), (10), (10);
EXPLAIN SELECT * FROM t1 WHERE a=10;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref a a 5 const 3 Using where
SELECT * FROM t1 WHERE a=10;
a
10
10
10
DROP TABLE t1;
CREATE TEMPORARY TABLE t1 (a int not null, primary key(a)) engine=MEMORY;
INSERT into t1 values (1),(2),(3),(4),(5),(6),(7),(8),(9),(10),(11);
DELETE from t1 where a < 100;
SELECT * from t1;
a
DROP TABLE t1;
CREATE TEMPORARY TABLE `job_titles` (
`job_title_id` int NOT NULL default '0',
`job_title` char(18) NOT NULL default '',
PRIMARY KEY (`job_title_id`),
UNIQUE KEY `job_title_id` (`job_title_id`,`job_title`)
) ENGINE=MEMORY;
SELECT MAX(job_title_id) FROM job_titles;
MAX(job_title_id)
NULL
DROP TABLE job_titles;
CREATE TEMPORARY TABLE t1 (a INT NOT NULL, B INT, KEY(B)) ENGINE=MEMORY;
INSERT INTO t1 VALUES(1,1), (1,NULL);
SELECT * FROM t1 WHERE B is not null;
a B
1 1
DROP TABLE t1;
CREATE TEMPORARY TABLE t1 (pseudo char(35) PRIMARY KEY, date int NOT NULL) ENGINE=MEMORY;
INSERT INTO t1 VALUES ('massecot',1101106491),('altec',1101106492),('stitch+',1101106304),('Seb Corgan',1101106305),('beerfilou',1101106263),('flaker',1101106529),('joce8',5),('M4vrick',1101106418),('gabay008',1101106525),('Vamp irX',1101106291),('ZoomZip',1101106546),('rip666',1101106502),('CBP ',1101106397),('guezpard',1101106496);
DELETE FROM t1 WHERE date<1101106546;
SELECT * FROM t1;
pseudo date
ZoomZip 1101106546
DROP TABLE t1;
create temporary table t1(a char(2)) engine=memory;
insert into t1 values (NULL), (NULL);
delete from t1 where a is null;
insert into t1 values ('2'), ('3');
select * from t1;
a
3
2
drop table t1;
set storage_engine=MEMORY;
create temporary table t1 (v varchar(10), c char(10), t varchar(50));
insert into t1 values('+ ', '+ ', '+ ');
set @a=repeat(' ',20);
insert into t1 values (concat('+',@a),concat('+',@a),concat('+',@a));
ERROR 22001: Data too long for column 'v' at row 1
set @a=repeat(' ',10);
insert into t1 values (concat('+',@a),concat('+',@a),concat('+',@a));
ERROR 22001: Data too long for column 'v' at row 1
set @a=repeat(' ',9);
insert into t1 values (concat('+',@a),concat('+',@a),concat('+',@a));
select concat('*',v,'*',c,'*',t,'*') from t1;
concat('*',v,'*',c,'*',t,'*')
*+ *+ *+ *
*+ *+ *+ *
show create table t1;
Table Create Table
t1 CREATE TEMPORARY TABLE `t1` (
`v` VARCHAR(10) COLLATE utf8_general_ci DEFAULT NULL,
`c` VARCHAR(10) COLLATE utf8_general_ci DEFAULT NULL,
`t` VARCHAR(50) COLLATE utf8_general_ci DEFAULT NULL
) ENGINE=MEMORY COLLATE = utf8_general_ci
create temporary table t2 like t1;
show create table t2;
Table Create Table
t2 CREATE TEMPORARY TABLE `t2` (
`v` VARCHAR(10) COLLATE utf8_general_ci DEFAULT NULL,
`c` VARCHAR(10) COLLATE utf8_general_ci DEFAULT NULL,
`t` VARCHAR(50) COLLATE utf8_general_ci DEFAULT NULL
) ENGINE=MEMORY COLLATE = utf8_general_ci
create temporary table t3 select * from t1;
show create table t3;
Table Create Table
t3 CREATE TEMPORARY TABLE `t3` (
`v` VARCHAR(10) COLLATE utf8_general_ci DEFAULT NULL,
`c` VARCHAR(10) COLLATE utf8_general_ci DEFAULT NULL,
`t` VARCHAR(50) COLLATE utf8_general_ci DEFAULT NULL
) ENGINE=MEMORY COLLATE = utf8_general_ci
alter table t1 modify c varchar(10);
show create table t1;
Table Create Table
t1 CREATE TEMPORARY TABLE `t1` (
`v` VARCHAR(10) COLLATE utf8_general_ci DEFAULT NULL,
`c` VARCHAR(10) COLLATE utf8_general_ci DEFAULT NULL,
`t` VARCHAR(50) COLLATE utf8_general_ci DEFAULT NULL
) ENGINE=MEMORY COLLATE = utf8_general_ci
alter table t1 modify v char(10);
show create table t1;
Table Create Table
t1 CREATE TEMPORARY TABLE `t1` (
`v` VARCHAR(10) COLLATE utf8_general_ci DEFAULT NULL,
`c` VARCHAR(10) COLLATE utf8_general_ci DEFAULT NULL,
`t` VARCHAR(50) COLLATE utf8_general_ci DEFAULT NULL
) ENGINE=MEMORY COLLATE = utf8_general_ci
alter table t1 modify t varchar(50);
show create table t1;
Table Create Table
t1 CREATE TEMPORARY TABLE `t1` (
`v` VARCHAR(10) COLLATE utf8_general_ci DEFAULT NULL,
`c` VARCHAR(10) COLLATE utf8_general_ci DEFAULT NULL,
`t` VARCHAR(50) COLLATE utf8_general_ci DEFAULT NULL
) ENGINE=MEMORY COLLATE = utf8_general_ci
select concat('*',v,'*',c,'*',t,'*') from t1;
concat('*',v,'*',c,'*',t,'*')
*+ *+ *+ *
*+ *+ *+ *
drop table t1,t2,t3;
create temporary table t1 (v varchar(10), c char(10), t varchar(50), key(v), key(c), key(t(10)));
show create table t1;
Table Create Table
t1 CREATE TEMPORARY TABLE `t1` (
`v` VARCHAR(10) COLLATE utf8_general_ci DEFAULT NULL,
`c` VARCHAR(10) COLLATE utf8_general_ci DEFAULT NULL,
`t` VARCHAR(50) COLLATE utf8_general_ci DEFAULT NULL,
KEY `v` (`v`) USING HASH,
KEY `c` (`c`) USING HASH,
KEY `t` (`t`(10)) USING HASH
) ENGINE=MEMORY COLLATE = utf8_general_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 43 const 10 Using where
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 43 const 10 Using where
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 43 const 10 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 ALL v NULL NULL NULL 271 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 43 const 10 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 43 const 10 Using where
alter table t1 add unique(v);
ERROR 23000: Duplicate entry '{ ' for key 'v_2'
select concat('*',v,'*',c,'*',t,'*') as qq from t1 where v='a' order by length(concat('*',v,'*',c,'*',t,'*'));
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 43 const 10 Using where
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 trim(v),count(t) from t1 group by v limit 10;
trim(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 trim(v),count(c) from t1 group by v limit 10;
trim(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 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 trim(t),count(t) from t1 group by t limit 10;
trim(t) 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 temporary 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 22001: Data too long for column 'a' at row 1
insert into t1 values ('a ');
ERROR 23000: Duplicate entry 'a ' for key 'a'
update t1 set a='a ' where a like 'a ';
update t1 set a='a ' where a like 'a ';
drop table t1;
create temporary table t1 (v varchar(10), c char(10), t varchar(50), key using btree (v), key using btree (c), key using btree (t(10)));
show create table t1;
Table Create Table
t1 CREATE TEMPORARY TABLE `t1` (
`v` VARCHAR(10) COLLATE utf8_general_ci DEFAULT NULL,
`c` VARCHAR(10) COLLATE utf8_general_ci DEFAULT NULL,
`t` VARCHAR(50) COLLATE utf8_general_ci DEFAULT NULL,
KEY `v` (`v`) USING BTREE,
KEY `c` (`c`) USING BTREE,
KEY `t` (`t`(10)) USING BTREE
) ENGINE=MEMORY COLLATE = utf8_general_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
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 43 const # Using where
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 43 const # Using where
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 43 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 ALL v NULL NULL 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 43 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 43 const # Using where
alter table t1 add unique(v);
ERROR 23000: Duplicate entry '{ ' for key 'v_2'
select concat('*',v,'*',c,'*',t,'*') as qq from t1 where v='a' order by length(concat('*',v,'*',c,'*',t,'*'));
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 43 const # Using where
drop table t1;
create temporary table t1 (a char(10), unique using btree (a)) engine=MEMORY;
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 22001: Data too long for column 'a' at row 1
insert into t1 values ('a ');
ERROR 23000: Duplicate entry 'a ' for key 'a'
update t1 set a='a ' where a like 'a ';
update t1 set a='a ' where a like 'a ';
drop table t1;
create temporary table t1 (v varchar(10), c char(10), t varchar(50), key(v(5)), key(c(5)), key(t(5)));
show create table t1;
Table Create Table
t1 CREATE TEMPORARY TABLE `t1` (
`v` VARCHAR(10) COLLATE utf8_general_ci DEFAULT NULL,
`c` VARCHAR(10) COLLATE utf8_general_ci DEFAULT NULL,
`t` VARCHAR(50) COLLATE utf8_general_ci DEFAULT NULL,
KEY `v` (`v`(5)) USING HASH,
KEY `c` (`c`(5)) USING HASH,
KEY `t` (`t`(5)) USING HASH
) ENGINE=MEMORY COLLATE = utf8_general_ci
drop table t1;
create temporary table t1 (v varchar(16383), key(v(10)));
show create table t1;
Table Create Table
t1 CREATE TEMPORARY TABLE `t1` (
`v` VARCHAR(16383) COLLATE utf8_general_ci DEFAULT NULL,
KEY `v` (`v`(10)) USING HASH
) ENGINE=MEMORY COLLATE = utf8_general_ci
insert into t1 values(repeat('a',16383));
select length(v) from t1 where v=repeat('a',16383);
length(v)
16383
drop table t1;
set storage_engine=InnoDB;
create temporary table t1 (a bigint auto_increment primary key, b int,
key (b, a)) engine=MEMORY;
insert t1 (b) values (1),(1),(1),(1),(1),(1),(1),(1);
select * from t1;
a b
1 1
2 1
3 1
4 1
5 1
6 1
7 1
8 1
drop table t1;
create temporary table t1 (a int not null, b int not null auto_increment,
primary key(a, b), key(b)) engine=MEMORY;
insert t1 (a) values (1),(1),(1),(1),(1),(1),(1),(1);
select * from t1;
a b
1 1
1 2
1 3
1 4
1 5
1 6
1 7
1 8
drop table t1;
create temporary table t1 (a int not null, b int not null auto_increment,
primary key(a, b)) engine=MEMORY;
ERROR 42000: Incorrect table definition; there can be only one auto column and it must be defined as a key
create temporary table t1 (c char(255), primary key(c(90)));
insert into t1 values ("abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz");
insert into t1 values ("abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz");
ERROR 23000: Duplicate entry 'abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijkl' for key 'PRIMARY'
drop table t1;
CREATE TEMPORARY TABLE t1 (a int, key(a)) engine=MEMORY;
insert into t1 values (0);
delete from t1;
select * from t1;
a
insert into t1 values (0), (1);
select * from t1 where a = 0;
a
0
drop table t1;
create temporary table t1 (c char(10)) engine=memory;
create temporary table t2 (c varchar(10)) engine=memory;
show table status like 't_';
Session Schema Name Type Engine Version Rows Avg_row_length Table_size Auto_increment
# test t1 TEMPORARY MEMORY # # # # #
# test t2 TEMPORARY MEMORY # # # # #
drop table t1, t2;
CREATE TEMPORARY TABLE t1(a VARCHAR(1), b VARCHAR(2), c VARCHAR(256),
KEY(a), KEY(b), KEY(c)) ENGINE=MEMORY;
INSERT INTO t1 VALUES('a','aa',REPEAT('a', 256)),('a','aa',REPEAT('a',256));
SELECT COUNT(*) FROM t1 WHERE a='a';
COUNT(*)
2
SELECT COUNT(*) FROM t1 WHERE b='aa';
COUNT(*)
2
SELECT COUNT(*) FROM t1 WHERE c=REPEAT('a',256);
COUNT(*)
2
DROP TABLE t1;
CREATE TEMPORARY TABLE t1(c1 VARCHAR(100), c2 INT) ENGINE=MEMORY;
INSERT INTO t1 VALUES('', 0);
ALTER TABLE t1 MODIFY c1 VARCHAR(101);
SELECT c2 FROM t1;
c2
0
DROP TABLE t1;
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