create table t1 (a tinyint unsigned 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` tinyint(3) unsigned NOT NULL,
  PRIMARY KEY (`a`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci
 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 (255), (254), (253), (252), (1), (2), (128);
select * from t1;
a
1
128
2
252
253
254
255
select * from t1 where a=253;
a
253
delete from t1 where a=253;
select * from t1;
a
1
128
2
252
254
255
drop table t1;
create table t2 (a tinyint unsigned not null, primary key(a)) engine='InnoDB' 
partition by key (a) partitions 8;
show create table t2;
Table	Create Table
t2	CREATE TABLE `t2` (
  `a` tinyint(3) unsigned NOT NULL,
  PRIMARY KEY (`a`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci
 PARTITION BY KEY (`a`)
PARTITIONS 8
insert into t2 values (255), (254), (253), (252);
select * from t2;
a
252
253
254
255
select * from t2 where a=253;
a
253
delete from t2 where a=253;
select * from t2;
a
252
254
255
delete from t2;
255 inserts;
select count(*) from t2;
count(*)
255
drop table t2;
create table t3 (a tinyint not null, primary key(a)) engine='InnoDB' 
partition by key (a) partitions 7;
show create table t3;
Table	Create Table
t3	CREATE TABLE `t3` (
  `a` tinyint(4) NOT NULL,
  PRIMARY KEY (`a`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci
 PARTITION BY KEY (`a`)
PARTITIONS 7
insert into t3 values (127), (126), (125), (124), (-128), (-127), (1), (-1), (0);
select * from t3;
a
-1
-127
-128
0
1
124
125
126
127
select * from t3 where a=125;
a
125
delete from t3 where a=125;
select * from t3;
a
-1
-127
-128
0
1
124
126
127
drop table t3;