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drop table if exists t1,t2,t3;
create table t1 (a int not null primary key auto_increment, message char(20));
create table t2 (a int not null primary key auto_increment, message char(20));
INSERT INTO t1 (message) VALUES ("Testing"),("table"),("t1");
INSERT INTO t2 (message) VALUES ("Testing"),("table"),("t2");
create table t3 (a int not null, b char(20), key(a)) type=MERGE UNION=(t1,t2);
select * from t3;
a b
1 Testing
2 table
3 t1
1 Testing
2 table
3 t2
select * from t3 order by a desc;
a b
3 t1
3 t2
2 table
2 table
1 Testing
1 Testing
drop table t3;
insert into t1 select NULL,message from t2;
insert into t2 select NULL,message from t1;
insert into t1 select NULL,message from t2;
insert into t2 select NULL,message from t1;
insert into t1 select NULL,message from t2;
insert into t2 select NULL,message from t1;
insert into t1 select NULL,message from t2;
insert into t2 select NULL,message from t1;
insert into t1 select NULL,message from t2;
insert into t2 select NULL,message from t1;
insert into t1 select NULL,message from t2;
create table t3 (a int not null, b char(20), key(a)) type=MERGE UNION=(test.t1,test.t2);
explain select * from t3 where a < 10;
table type possible_keys key key_len ref rows Extra
t3 range a a 4 NULL 10 where used
explain select * from t3 where a > 10 and a < 20;
table type possible_keys key key_len ref rows Extra
t3 range a a 4 NULL 10 where used
select * from t3 where a = 10;
a b
10 Testing
10 Testing
select * from t3 where a < 10;
a b
1 Testing
1 Testing
2 table
2 table
3 t1
3 t2
4 Testing
4 Testing
5 table
5 table
6 t1
6 t2
7 Testing
7 Testing
8 table
8 table
9 t2
9 t2
select * from t3 where a > 10 and a < 20;
a b
11 table
11 table
12 t1
12 t1
13 Testing
13 Testing
14 table
14 table
15 t2
15 t2
16 Testing
16 Testing
17 table
17 table
18 t2
18 t2
19 Testing
19 Testing
explain select a from t3 order by a desc limit 10;
table type possible_keys key key_len ref rows Extra
t3 index NULL a 4 NULL 1131 Using index
select a from t3 order by a desc limit 10;
a
699
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690
select a from t3 order by a desc limit 300,10;
a
416
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show create table t3;
Table Create Table
t3 CREATE TABLE `t3` (
`a` int(11) NOT NULL default '0',
`b` char(20) default NULL,
KEY `a` (`a`)
) TYPE=MRG_MyISAM UNION=(t1,t2)
create table t4 (a int not null, b char(10), key(a)) type=MERGE UNION=(t1,t2);
select * from t4;
Can't open file: 't4.MRG'. (errno: 143)
create table t5 (a int not null, b char(10), key(a)) type=MERGE UNION=(test.t1,test_2.t2);
Incorrect table definition; All MERGE tables must be in the same database
drop table if exists t5,t4,t3,t1,t2;
create table t1 (c char(10)) type=myisam;
create table t2 (c char(10)) type=myisam;
create table t3 (c char(10)) union=(t1,t2) type=merge;
insert into t1 (c) values ('test1');
insert into t1 (c) values ('test1');
insert into t1 (c) values ('test1');
insert into t2 (c) values ('test2');
insert into t2 (c) values ('test2');
insert into t2 (c) values ('test2');
select * from t3;
c
test1
test1
test1
test2
test2
test2
select * from t3;
c
test1
test1
test1
test2
test2
test2
delete from t3 where 1=1;
select * from t3;
c
select * from t1;
c
drop table t3,t2,t1;
CREATE TABLE t1 (incr int not null, othr int not null, primary key(incr));
CREATE TABLE t2 (incr int not null, othr int not null, primary key(incr));
CREATE TABLE t3 (incr int not null, othr int not null, primary key(incr))
TYPE=MERGE UNION=(t1,t2);
SELECT * from t3;
incr othr
INSERT INTO t1 VALUES ( 1,10),( 3,53),( 5,21),( 7,12),( 9,17);
INSERT INTO t2 VALUES ( 2,24),( 4,33),( 6,41),( 8,26),( 0,32);
INSERT INTO t1 VALUES (11,20),(13,43),(15,11),(17,22),(19,37);
INSERT INTO t2 VALUES (12,25),(14,31),(16,42),(18,27),(10,30);
SELECT * from t3 where incr in (1,2,3,4) order by othr;
incr othr
1 10
2 24
4 33
3 53
alter table t3 UNION=(t1);
select count(*) from t3;
count(*)
10
alter table t3 UNION=(t1,t2);
select count(*) from t3;
count(*)
20
alter table t3 TYPE=MYISAM;
select count(*) from t3;
count(*)
20
drop table t3;
CREATE TABLE t3 (incr int not null, othr int not null, primary key(incr))
TYPE=MERGE UNION=(t1,t2);
show create table t3;
Table Create Table
t3 CREATE TABLE `t3` (
`incr` int(11) NOT NULL default '0',
`othr` int(11) NOT NULL default '0',
PRIMARY KEY (`incr`)
) TYPE=MRG_MyISAM UNION=(t1,t2)
alter table t3 drop primary key;
show create table t3;
Table Create Table
t3 CREATE TABLE `t3` (
`incr` int(11) NOT NULL default '0',
`othr` int(11) NOT NULL default '0'
) TYPE=MRG_MyISAM UNION=(t1,t2)
drop table t3,t2,t1;
create table t1 (a int not null) type=merge;
select * from t1;
a
drop table t1;
drop table if exists t3, t2, t1;
create table t1 (a int not null, b int not null, key(a,b));
create table t2 (a int not null, b int not null, key(a,b));
create table t3 (a int not null, b int not null, key(a,b)) TYPE=MERGE UNION=(t1,t2);
insert into t1 values (1,2),(2,1),(0,0),(4,4),(5,5),(6,6);
insert into t2 values (1,1),(2,2),(0,0),(4,4),(5,5),(6,6);
flush tables;
select * from t3 where a=1 order by b limit 2;
a b
1 1
1 2
drop table t3,t1,t2;
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