alter table performance_schema.user_variables_by_thread
add column foo integer;
ERROR 42000: Access denied for user 'root'@'localhost' to database 'performance_schema'
truncate table performance_schema.user_variables_by_thread;
ERROR HY000: Invalid performance_schema usage.
ALTER TABLE performance_schema.user_variables_by_thread
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.user_variables_by_thread(VARIABLE_NAME);
ERROR 42000: Access denied for user 'root'@'localhost' to database 'performance_schema'