select @@global.myisam_block_size;
@@global.myisam_block_size
1024
select @@session.myisam_block_size;
ERROR HY000: Variable 'myisam_block_size' is a GLOBAL variable
show global variables like 'myisam_block_size';
Variable_name	Value
myisam_block_size	1024
show session variables like 'myisam_block_size';
Variable_name	Value
myisam_block_size	1024
select * from information_schema.global_variables where variable_name='myisam_block_size';
VARIABLE_NAME	VARIABLE_VALUE
MYISAM_BLOCK_SIZE	1024
select * from information_schema.session_variables where variable_name='myisam_block_size';
VARIABLE_NAME	VARIABLE_VALUE
MYISAM_BLOCK_SIZE	1024
set global myisam_block_size=1;
ERROR HY000: Variable 'myisam_block_size' is a read only variable
set session myisam_block_size=1;
ERROR HY000: Variable 'myisam_block_size' is a read only variable
