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