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
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