166、
166.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 参考：Performance Tuning Guide You can maintain optimizer statistics manually using the DBMS_STATSpackage. 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.
167、
167.Automatic Shared Memory Management is disabled for your database instance. You realize that there are cases of SQL statements performing poorly because of repeated parsing activity, resulting in degradation of performance. What would be your next step to improve performance? A. Run the SQL Access Advisor B. Run the memory Advisor for the SGA C. Run the memory Advisor for the PGA D. Run the memory advisor for the shared pool E. Run the memory advisor for the buffer cache
Answer: D 共享池（shared pool）共享sql或pl/sql代码，把解析得到的sql代码的结果在这里缓存 共享池由两部分组成：库高速缓存、数据字典高速缓存。 库高速缓存存储最近使用过的sql和pl/sql语句 数据字典高速缓存存储数据文件、表、索引、列、用户、权限信息和其他一些数据库对象的定义。
168、View the Exhibit and examine the parameters.
User A executes the following command to update the TRANS table: SQL> UPDATE B.trans SET tr_amt=tr_amt+500 WHERE c_code='C005'; Before user A issues a COMMIT or ROLLBACK command, user B executes the following command on the TRANS table: SQL> ALTER TABLE trans MODIFY (tr_type VARCHAR2(3)); What would happen in this scenario? A. The ALTER TABLE command modifies the column successfully B. The DDL operation gets higher priority and transaction for user A is rolled back C. The ALETER TABLE command waits indefinitely until user A ends the transaction D. The ALTER TABLE command fails after waiting for 60 seconds due to the resource being busy
Answer: D 11g以前，DDL 语句是不会等待DML语句的，当DDL语句访问的对象正在执行的DML语句，会立即报错ORA-00054: resource busy and acquire with NOWAIT specified。而在11g以后，DDL_LOCK_TIMEOUT参数可以修改这一状态，当DDL_LOCK_TIMEOUT=0时，DDL 不等待DML，当DDL_LOCK_TIMEOUT 为N（秒）时，DDL等待DML N 秒！
169、
169.Which two files in the database can be configured for automatic backups by using the autobackup feature in Recovery Manager (RMAN)? (Choose two.) A. Data Files B. Control Files C. Parameter Files D. Online Redo Log Files E. Server Parameter File
Answer: BE
170、
170.Which two statements are true regarding the usage of the SQL*LOADER utility? (Choose two.) A. You can load data into multiple tables during the same load session B. You can load data from multiple files to a table during the same load session C. You cannot perform selective data loading based on the values available in the records D. You can use an export file generated by the EXPDP utility as an input data file to load the data E. You can load data only if the input file is available on the disk and tape but not a named pipes
Answer: AB
