2、Which two are true about Optimizer Statistics? ? A) They do not persist across Instance restarts. ? B) They are automatically updated when DDL statements execute. ? C) They are gathered by the Manageability Monitor (MMON) background process. ? D) They can be gathered by executing the PL/SQL procedures in the DBMS_STATS package. ? E) They can be used to determine the events on which a database instance waited. ? F) They provide Information to the Optimizer so that it can determine optimal execution plans for SQL statements. ? Answer:DF
