alter table performance_schema.global_variables
add column foo integer;
ERROR 42000: Access denied for user 'root'@'localhost' to database 'performance_schema'
truncate table performance_schema.global_variables;
ERROR HY000: Invalid performance_schema usage
ALTER TABLE performance_schema.global_variables
ADD INDEX test_index(VARIABLE_NAME);
ERROR 42000: Access denied for user 'root'@'localhost' to database 'performance_schema'
CREATE UNIQUE INDEX test_index
ON performance_schema.global_variables(VARIABLE_NAME);
ERROR 42000: Access denied for user 'root'@'localhost' to database 'performance_schema'