1select @@global.max_long_data_size=20; 2@@global.max_long_data_size=20 30 4select @@session.max_long_data_size; 5ERROR HY000: Variable 'max_long_data_size' is a GLOBAL variable 6SELECT @@global.max_long_data_size = VARIABLE_VALUE 7FROM INFORMATION_SCHEMA.GLOBAL_VARIABLES 8WHERE VARIABLE_NAME='max_long_data_size'; 9@@global.max_long_data_size = VARIABLE_VALUE 101 11set global max_long_data_size=1; 12ERROR HY000: Variable 'max_long_data_size' is a read only variable 13set session max_long_data_size=1; 14ERROR HY000: Variable 'max_long_data_size' is a read only variable 15