40. You have statistics collected for some selected tables. Your requirement is that the statistics for the
tables and all dependent indexes must not be overwritten by further statistics collection until a certain
point of time.
How would you achieve this?
A.Lock statistics for the tables.
B.Change STALE_PERCENT to zero for the tables.
C.Set the TIMED_STATISTICS parameter to TRUE.
D.Set the STATISTICS_LEVEL parameter to BASIC.
E.Set the OPTIMIZER_USE_PENDING parameter statistics to TRUE.
Answer: A
答案解析：
参考：http://docs.oracle.com/cd/E11882_01/server.112/e41573/stats.htm#PFGRF94712
You can maintain optimizer statistics manually using the DBMS_STATS package. For example, you can save and restore copies of
statistics. You can export statistics from one database and import those statistics into another database. For example, you can export statistics from a production system to a test system. You can also lock statistics to
prevent them from changing.