key partition

[jongse park]

How many partition does mysql have the best performance with key partition?

This is table script

CREATE TABLE key_partition
(
ORD_ID VARCHAR(19) NOT NULL,
DGA_ID VARCHAR(10) NULL,
GDGD_DT DATETIME NULL,
LGKD_ID VARCHAR(24) NULL,
DD_CD VARCHAR(6) NULL,
IEGE VARCHAR(20) NULL,
MCD VARCHAR(10) NULL,
PEI VARCHAR(10) NULL,
USR_ID VARCHAR(10) NOT NULL,
PRIMARY KEY (ORD_ID, USR_ID)
)
PARTITION BY KEY (USR_ID)
PARTITONS 100
;

How about partitions 100 ?