SET @start_global_value = @@global.ROCKSDB_ENABLE_THREAD_TRACKING; SELECT @start_global_value; @start_global_value 1 "Trying to set variable @@global.ROCKSDB_ENABLE_THREAD_TRACKING to 444. It should fail because it is readonly." SET @@global.ROCKSDB_ENABLE_THREAD_TRACKING = 444; ERROR HY000: Variable 'rocksdb_enable_thread_tracking' is a read only variable