201、
201.Why does performance degrade when many UPDATE, INSERT or DELETE statements are issued on a table that has an associated bitmap index? A. The DML operations re-create the bitmap index blocks B. The bitmap index is rebuilt automatically after a DML operation C. The smallest amount of a bitmap that can be locked is a bitmap segment D. Additional time is taken to remove NULL values from the bitmap index after a DML operation
Answer: C
位图索引使用场景
202、View the Exhibit and examine the undo tablespace attributes.
Your database instance is experiencing a large volume of transactions from non-DBA users in the last one hour. The undo tablespace NDOTBS1 is full with transactions and no transaction was committed more than one hour ago. The database has two more undo tablespaces. What happens to the new DML operations in this scenario? A. The DML commands will fail B. The undo data generated by the DML is stored in one of the two other undo tablespace C. The undo data generated by the DML will overwrite the extents that contain committed undo data D. The undo data generated by the DML is stored in the SYSTEM undo segment of the SYSTEM tablespace
Answer: A
undo retention的时间为60分钟。
retention guarantee 设置为yes
auto_extensible设置为no
203、
203.You want to configure and schedule offline database backups to run automatically. Which tool or utility would you use to achieve this? A. The XML script B. The PL/SQL script C. The DBMS_SCHEDULER package D. Enterprise Manager to schedule the backup
Answer: D
204、
204.In which of the scenario will the DBA perform recovery? (Choose all that apply.) A. The alert log file is corrupted B. A tablespace is accidentally dropped C. One of the redo log members is corrupted D. A database user terminates the session abnormally E. The hard disk on which the data files is stored is corrupted
Answer: BE
205、
205.Which two statements are true regarding undo tablespaces? (Choose two.) A. The database can have more than one undo tablespace B. The UNDO_TABLESPACE parameter is valid in both automatic and manual undo management C. Undo segments automatically grow and shrink as needed, acting as circular storage buffer for their assigned transactions D. An undo tablespace is automatically created if the UNDO_TABLESPACE parameter is not set and the UNDO_MANAGEMENT parameter is set to AUTO during the database instance start up
Answer: AC UNDO_TABLESPACE Optional, and valid only in automatic undo management mode. oracle数据库中一个实例只允许有一个活跃的还原表空间，且可以通过动态的方式切换还原表空间。 D： 是由DBCA自动创建或者由create database时手动创建或者create unod tablespace手动创建。 不是数据库启动时。