create table t1 (a float 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` float NOT NULL, PRIMARY KEY (`a`) ) ENGINE=MyISAM DEFAULT CHARSET=latin1 /*!50100 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 (-3.402823466E+38), (3.402823466E+38), (-1.5), (-1), (0), (1), (1.5); select * from t1; a -3.40282e38 -1.5 -1 0 1 1.5 3.40282e38 select * from t1 where a=1.5; a 1.5 delete from t1 where a=1.5; select * from t1; a -3.40282e38 -1.5 -1 0 1 3.40282e38 drop table t1; create table t2 (a float 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` float NOT NULL, PRIMARY KEY (`a`) ) ENGINE=MyISAM DEFAULT CHARSET=latin1 /*!50100 PARTITION BY KEY (a) PARTITIONS 10 */ insert into t2 values (-3.402823466E+38), (-3.402823466E+37), (-123.456), (0), (1234546.789), (123.456), (1.5); select * from t2; a -3.40282e38 -3.40282e37 -123.456 0 1.5 123.456 1234550 select * from t2 where a=123.456; a delete from t2 where a=123.456; select * from t2; a -3.40282e38 -3.40282e37 -123.456 0 1.5 123.456 1234550 select * from t2 where a=1.5; a 1.5 delete from t2 where a=1.5; select * from t2; a -3.40282e38 -3.40282e37 -123.456 0 123.456 1234550 delete from t2; 16384*3 inserts; select count(*) from t2; count(*) 49152 drop table t2; 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 /*!50100 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 /*!50100 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;