297.View the Exhibit for some of the parameter settings. You start a session and issue the following command:
SQL>CREATE INDEX emp_ename ON emp(ename) TABLESPACE users INVISIBLE;
What is the outcome of the above command?
A. The index is not used by the optimizer but is maintained during DML operations.
B. The index is not used by the optimizer and is not maintained during DML operations.
C. The index is used by the optimizer only if a hint is specified in the query statement and is maintained during DML operations.
D. The index is used by the optimizer only if a hint is specified in the query statement but is not maintained during DML operations.
Answer: A
答案解析：
参考：http://docs.oracle.com/cd/E11882_01/server.112/e40540/glossary.htm#CNCPT89261
invisible index
An index that is maintained by DML operations, but is not used by default by the optimizer. Making an index invisible is an alternative to making it unusable or dropping it.