052(一）

1、

1.The instance abnormally terminates because of a power outage. 
Which statement is true about redo log files during instance recovery? 
A. Inactive and current redo log files are required to accomplish recovery 
B. Online and archived redo files are required to accomplish instance recovery 
C. All redo log entries after the last checkpoint are applied from redo log files to data files 
D. All redo log entries recorded in the current log file until the checkpoint position are applied to data files 

Answer: C 

 

Oracle维护着两类重做日志文件：在线（online）重做日志文件和归档（archived）重做日志文件。这两类重做日志文件都用于恢复；其主要目的是，万一实例失败或介质失败，它们就能派上用场。

如果数据库所在主机掉电，导致实例失败，Oracle 会使用在线重做日志将系统恰好恢复到掉电之前的那个时间点。

如果磁盘驱动器出现故障（这是一个介质失败），Oracle 会 使用归档重做日志以及在线重做日志将该驱动器上的数据备份恢复到适当的时间点。另外，如果你“无意地”截除了一个表，或者删除了某些重要的信息，然后提交 了这个操作，那么可以恢复受影响数据的一个备份，并使用在线和归档重做日志文件把它恢复到这个“意外”发生前的时间点。

 

2、

2.Examine the command: 
SQL>ALTER USR skd ACCOUNT LOCK; 
Which two statements are true after the command is executed.? (Choose two.) 
A. The SKD user cannot log in to the database instance 
B. The objects owned by the SKD user are not accessible to any user 
C. The other users can access the objects owned by the SKD user, on which they have access 
D. The password for the SKD user expires and the user is forced to change the password at the next login
Answer: AC 

用户被锁住，其他用户还是可以访问该用户下的对象，并且能在该用户下创建对象。

只是用户本身不能登录，需要管理员解锁。

 

3、

3.For which database operation would you need the database to be in the MOUNT state? 
A. Renaming the control files 
B. Re-creating the control files 
C. Dropping a user in your database 
D. Dropping a tablespace in your database 
E. Configuring the database instance to operate in the ARCHIVELOG or NOARCHIVELOG modes 
Answer: E 

考察点：

数据库启动三个步骤：

启动实例

挂载（mount）数据库

打开（open）数据库

　　当 Oracle 启动实例时，首先需要从服务器参数文件（server parameter file）或初始化参数文件（initialization parameter file）中读取初始化参数，之后创建存储数据库信息的共享内存区 SGA，最后创建后台进程（background process）。此时，构成实例的内存区及进程还没有和数据库产生联系。

　　Oracle 将数据库挂载（mount）到实例，以便实例和数据库共同工作。在挂载数据库时，实例首先需要找到并打开数据库控制文件（control file）。控制文件的名称及位置信息记录在参数文件的 CONTROL_FILES 参数中。接着 Oracle 将读取控制文件获取数据库的数据文件（datafile）名及重做日志文件（redo log file）名。

　　打开数据库时，Oracle 将打开所有联机的数据文件（datafile）及重做日志文件（redo log file）。如果数据库上次停止时某个表空间处于脱机状态，那么打开数据库时此表空间及相关的数据文件将依旧处于脱机状态。如果 Oracle 在打开数据库时找不到所需的数据文件或重做日志文件，系统将返回错误信息。管理员必须从备份中恢复损坏或缺失的文件后，才能打开数据库。

 

修改归档模式需要在mount下进行。

 

4、

4.The job to gather optimizer statistics for objects runs as part of the automatic maintenance window in 
your database instance. At a certain point of time, the maintenance window closes before the statistics 
are gathered for all objects.
Which statement is true in this scenario?
A. The statistics collection continues until all objects are processed. 
B. The job is terminated and the statistics collected are restored to a time before the job started. 
C. This produces an error and the statistics collected are locked until the next time that the maintenance 
window is opened. 
D. The job is terminated and the statistics for the remaining objects are collected the next time that the 
maintenance window is opened. 
Answer: D 

 

Automatic optimizer statistics collection calls the DBMS_STATS.GATHER_DATABASE_STATS_JOB_PROC procedure. This internal procedure operates similarly to the DBMS_STATS.GATHER_DATABASE_STATS procedure using the GATHER AUTO option. The main difference is thatGATHER_DATABASE_STATS_JOB_PROC prioritizes database objects that require statistics, so that objects that most need updated statistics are processed first, before the maintenance window closes.

统计信息分析优先级

5、

5.You want to move all objects of the APPS user in the test database to the DB_USR schema of the 
production database. 
Which option of IMPDP would you use to accomplish this task? 
A. FULL 
B. SCHEMAS 
C. TRANSFORM 
D. REMAP_SCHEMA
E. REMAP_TABLESPACE 
Answer: D 

The REMAP_SCHEMA parameter changes the ownership of database objects. If you do not specify REMAP_SCHEMA, all database objects (such as tables and indexes) are created in the same user schema as in the source database, and those users must already exist in the destination database.

 例如:

impdp system dumpfile=expdat.dmp directory=data_pump_dir 
TRANSPORT_DATAFILES=
c:\app\orauser\oradata\orawin\sales_101.dbf,
c:\app\orauser\oradata\orawin\sales_201.dbf
remap_schema=sales1:crm1 remap_schema=sales2:crm2
logfile=tts_import.log