mariadb/mysql-test/r/heap.result

drop table if exists t1,t2,t3;
create table t1 (a int not null,b int not null, primary key (a)) engine=heap comment="testing heaps" avg_row_length=100 min_rows=1 max_rows=100;
insert into t1 values(1,1),(2,2),(3,3),(4,4);
delete from t1 where a=1 or a=0;
show keys from t1;
Table	Non_unique	Key_name	Seq_in_index	Column_name	Collation	Cardinality	Sub_part	Packed	Null	Index_type	Comment	Index_comment
t1	0	PRIMARY	1	a	NULL	3	NULL	NULL		HASH		
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 not null, add key (c,a);
drop table t1;
create 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 table t1 (a int not null,b int not null, primary key (a)) engine=heap 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=myisam, comment="new myisam table";
select * from t1;
a	b
1	1
2	2
3	3
4	4
drop table t1;
create table t1 (a int not null) engine=heap;
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
alter table t1 engine=myisam;
explain select * from t1 where a in (869751,736494,226312,802616);
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1	range	uniq_id	uniq_id	4	NULL	4	Using where; Using index
drop table t1;
create table t1 (x int not null, y int not null, key x (x), unique y (y))
engine=heap;
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;
x	y	x	y
1	1	1	1
2	2	2	2
1	3	1	1
2	4	2	2
2	5	2	2
2	6	2	2
explain select * from t1,t1 as t2 where t1.x=t2.y;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1	ALL	x	NULL	NULL	NULL	6	
1	SIMPLE	t2	eq_ref	y	y	4	test.t1.x	1	
drop table t1;
create table t1 (a int) engine=heap;
insert into t1 values(1);
select max(a) from t1;
max(a)
1
drop table t1;
CREATE TABLE t1 ( a int not null default 0, b int not null default 0,  key(a),  key(b)  ) ENGINE=HEAP;
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 table t1 (id int unsigned not null, primary key (id)) engine=HEAP;
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 table t1 (n int) engine=heap;
drop table t1;
create table t1 (n int) engine=heap;
drop table if exists t1;
CREATE table t1(f1 int not null,f2 char(20) not 
null,index(f2)) engine=heap;
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 table t1 (btn char(10) not null, key(btn)) engine=heap;
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) 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	11	const,const	2	Using where
drop table t1;
CREATE TABLE t1 (
a int default NULL,
b int default NULL,
KEY a (a),
UNIQUE b (b)
) engine=heap;
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 TABLE t1 (
a int default NULL,
key a (a)
) ENGINE=HEAP;
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 TABLE t1 (a int not null, primary key(a)) engine=heap;
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 TABLE `job_titles` (
`job_title_id` int(6) unsigned 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=HEAP;
SELECT MAX(job_title_id) FROM job_titles;
MAX(job_title_id)
NULL
DROP TABLE job_titles;
CREATE TABLE t1 (a INT NOT NULL, B INT, KEY(B)) ENGINE=HEAP;
INSERT INTO t1 VALUES(1,1), (1,NULL);
SELECT * FROM t1 WHERE B is not null;
a	B
1	1
DROP TABLE t1;
CREATE TABLE t1 (pseudo char(35) PRIMARY KEY, date int(10) unsigned NOT NULL) ENGINE=HEAP;
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 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=HEAP;
create 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));
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` varchar(50) DEFAULT NULL
) ENGINE=MEMORY DEFAULT CHARSET=latin1
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` varchar(50) DEFAULT NULL
) ENGINE=MEMORY DEFAULT CHARSET=latin1
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` varchar(50) DEFAULT NULL
) ENGINE=MEMORY DEFAULT CHARSET=latin1
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` varchar(50) DEFAULT NULL
) ENGINE=MEMORY DEFAULT CHARSET=latin1
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` varchar(50) DEFAULT NULL
) ENGINE=MEMORY DEFAULT CHARSET=latin1
alter table t1 modify t varchar(10);
Warnings:
Warning	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=MEMORY DEFAULT CHARSET=latin1
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 varchar(50), 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` varchar(50) DEFAULT NULL,
  KEY `v` (`v`),
  KEY `c` (`c`),
  KEY `t` (`t`(10))
) ENGINE=MEMORY DEFAULT CHARSET=latin1
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	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	11	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	13	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	13	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	13	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	13	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 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 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 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 ';
update t1 set a='a  ' where a like 'a      ';
drop table t1;
create 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 TABLE `t1` (
  `v` varchar(10) DEFAULT NULL,
  `c` char(10) DEFAULT NULL,
  `t` varchar(50) DEFAULT NULL,
  KEY `v` (`v`) USING BTREE,
  KEY `c` (`c`) USING BTREE,
  KEY `t` (`t`(10)) USING BTREE
) ENGINE=MEMORY DEFAULT CHARSET=latin1
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	13	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	11	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	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
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
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
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	13	const	#	Using where
drop table t1;
create table t1 (a char(10), unique using btree (a)) engine=heap;
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 ';
update t1 set a='a  ' where a like 'a      ';
drop table t1;
create 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 TABLE `t1` (
  `v` varchar(10) DEFAULT NULL,
  `c` char(10) DEFAULT NULL,
  `t` varchar(50) DEFAULT NULL,
  KEY `v` (`v`(5)),
  KEY `c` (`c`(5)),
  KEY `t` (`t`(5))
) ENGINE=MEMORY DEFAULT CHARSET=latin1
drop table t1;
create table t1 (v varchar(65530), key(v(10)));
show create table t1;
Table	Create Table
t1	CREATE TABLE `t1` (
  `v` varchar(65530) DEFAULT NULL,
  KEY `v` (`v`(10))
) ENGINE=MEMORY DEFAULT CHARSET=latin1
insert into t1 values(repeat('a',65530));
select length(v) from t1 where v=repeat('a',65530);
length(v)
65530
drop table t1;
set storage_engine=MyISAM;
create table t1 (a bigint unsigned auto_increment primary key, b int,
key (b, a)) engine=heap;
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 table t1 (a int not null, b int not null auto_increment,
primary key(a, b), key(b)) engine=heap;
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 table t1 (a int not null, b int not null auto_increment,
primary key(a, b)) engine=heap;
ERROR 42000: Incorrect table definition; there can be only one auto column and it must be defined as a key
create 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 TABLE t1 (a int, key(a)) engine=heap;
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 table t1 (c char(10)) engine=memory;
create table t2 (c varchar(10)) engine=memory;
show table status like 't_';
Name	Engine	Version	Row_format	Rows	Avg_row_length	Data_length	Max_data_length	Index_length	Data_free	Auto_increment	Create_time	Update_time	Check_time	Collation	Checksum	Create_options	Comment
t1	MEMORY	10	Fixed	0	11	0	#	0	0	NULL	NULL	NULL	NULL	latin1_swedish_ci	NULL		
t2	MEMORY	10	Fixed	0	12	0	#	0	0	NULL	NULL	NULL	NULL	latin1_swedish_ci	NULL		
drop table t1, t2;
CREATE 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 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;