create table t1 (a decimal(10,4) not null, primary key(a)) engine='InnoDB' 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` decimal(10,4) NOT NULL, PRIMARY KEY (`a`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 /*!50100 PARTITION BY KEY (a) (PARTITION pa1 MAX_ROWS = 20 MIN_ROWS = 2 ENGINE = InnoDB, PARTITION pa2 MAX_ROWS = 30 MIN_ROWS = 3 ENGINE = InnoDB, PARTITION pa3 MAX_ROWS = 30 MIN_ROWS = 4 ENGINE = InnoDB, PARTITION pa4 MAX_ROWS = 40 MIN_ROWS = 2 ENGINE = InnoDB) */ insert into t1 values (999999.9999), (-999999.9999), (123456.7899), (-123456.7899), (-1.5), (1), (0), (-1), (1.5), (1234.567), (-1234.567); select * from t1; a -999999.9999 -123456.7899 -1234.5670 -1.5000 -1.0000 0.0000 1.0000 1.5000 1234.5670 123456.7899 999999.9999 select * from t1 where a=1234.567; a 1234.5670 delete from t1 where a=1234.567; select * from t1; a -999999.9999 -123456.7899 -1234.5670 -1.5000 -1.0000 0.0000 1.0000 1.5000 123456.7899 999999.9999 drop table t1; create table t2 (a decimal(18,9) not null, primary key(a)) engine='InnoDB' partition by key (a) partitions 10; show create table t2; Table Create Table t2 CREATE TABLE `t2` ( `a` decimal(18,9) NOT NULL, PRIMARY KEY (`a`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 /*!50100 PARTITION BY KEY (a) PARTITIONS 10 */ insert into t2 values (999999999.999999999), (-999999999.999999999), (-1.5), (-1), (0), (1.5), (1234.567), (-1234.567); select * from t2; a -999999999.999999999 -1234.567000000 -1.500000000 -1.000000000 0.000000000 1.500000000 1234.567000000 999999999.999999999 select * from t2 where a=1234.567; a 1234.567000000 delete from t2 where a=1234.567; select * from t2; a -999999999.999999999 -1234.567000000 -1.500000000 -1.000000000 0.000000000 1.500000000 999999999.999999999 delete from t2; 1024*3 inserts; select count(*) from t2; count(*) 3072 drop table t2;