OCP-1Z0-053-V13.02-489题

489.For which two database objects can the VERSIONS clause of the Flashback Versions Query be used?(Choose two.)

A.views

B.fixed tables

C.heap tables

D.external tables

E.temporary tables

F.index-organized tables (IOT)

Answer: CF

答案解析：

参考：http://docs.oracle.com/cd/E11882_01/server.112/e41084/statements_10002.htm#SQLRF55624

排除法，选择CF

Restrictions on Flashback Queries These queries are subject to the following restrictions:

• You cannot specify a column expression or a subquery in the expression of the AS OF clause.

• You cannot specify the AS OF clause if you have specified the for_update_clause.

• You cannot use the AS OF clause in the defining query of a materialized view.

• You cannot use the VERSIONS clause in flashback queries to temporary or external tables, or tables that are part of a cluster.

• You cannot use the VERSIONS clause in flashback queries to views. However, you can use the VERSIONS syntax in the defining query of a view.

• You cannot specify the flashback_query_clause if you have specified query_name in the query_table_expression.

  
  

  
  

  
  

 参考：http://docs.oracle.com/cd/E11882_01/appdev.112/e41502/adfns_flashback.htm#ADFNS01005

Flashback Version Query allows index-only access only with IOTs (index-organized tables), but index fast full scan is not allowed.