create table t1 (a double not null, primary key(a)) engine='MYISAM' 
partition by key (a) (
partition pa1 max_rows=20 min_rows=2,
partition pa2 max_rows=30 min_rows=3,
partition pa3 max_rows=30 min_rows=4,
partition pa4 max_rows=40 min_rows=2);
show create table t1;
Table	Create Table
t1	CREATE TABLE `t1` (
  `a` double NOT NULL,
  PRIMARY KEY (`a`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1
 PARTITION BY KEY (`a`)
(PARTITION `pa1` MAX_ROWS = 20 MIN_ROWS = 2 ENGINE = MyISAM,
 PARTITION `pa2` MAX_ROWS = 30 MIN_ROWS = 3 ENGINE = MyISAM,
 PARTITION `pa3` MAX_ROWS = 30 MIN_ROWS = 4 ENGINE = MyISAM,
 PARTITION `pa4` MAX_ROWS = 40 MIN_ROWS = 2 ENGINE = MyISAM)
insert into t1 values (-2.2250738585072014E+208), (-2.2250738585072014E-208), (-1.5), (-1), (0), (1.5), (1234.567), (2.2250738585072014E+208);
select * from t1;
a
-2.2250738585072016e208
-1.5
-1
-2.2250738585072014e-208
0
1.5
1234.567
2.2250738585072016e208
select * from t1 where a=1.5;
a
1.5
delete from t1 where a=1.5;
select * from t1;
a
-2.2250738585072016e208
-1.5
-1
-2.2250738585072014e-208
0
1234.567
2.2250738585072016e208
drop table t1;
create table t2 (a double not null, primary key(a)) engine='MYISAM' 
partition by key (a) partitions 10;
show create table t2;
Table	Create Table
t2	CREATE TABLE `t2` (
  `a` double NOT NULL,
  PRIMARY KEY (`a`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1
 PARTITION BY KEY (`a`)
PARTITIONS 10
insert into t2 values (-2.2250738585072014E+208), (-2.2250738585072014E-208), (-1.5), (-1), (0), (1.5), (1234.567), (2.2250738585072014E+208);
select * from t2;
a
-2.2250738585072016e208
-1.5
-1
-2.2250738585072014e-208
0
1.5
1234.567
2.2250738585072016e208
select * from t2 where a=1234.567;
a
1234.567
delete from t2 where a=1234.567;
select * from t2;
a
-2.2250738585072016e208
-1.5
-1
-2.2250738585072014e-208
0
1.5
2.2250738585072016e208
delete from t2;
16384*3 inserts;
select count(*) from t2;
count(*)
49152
drop table t2;