Oracle公司頒佈並實施的一項權威品的服務與支援。並具有嫻熟的專業技術標準，它是專為認證那些有操作能力與廣泛理論知識的專業人。下面是小編整理的Oracle OCP認證考試題庫解析，歡迎大家參考!
QUESTION 1
You notice that the performance of the database has degraded because of frequent checkpoints.
Which two actions resolve the issue? (Choose two.)
A. Disable automatic checkpoint tuning
B. Check the size of the redo log file size and increase the size if it is small
C. Set the FAST_START_MTTR_TARGET parameter as per the advice given by the MTTR Advisor
D. Decrease the number of redo log members if there are more than one redo log members available in each redo log group
Correct Answer: BC
Explanation/Reference:
檢查點程序:
The checkpoint process (CKPT) updates the control file and data file headers with checkpoint information and signals DBWn to write blocks to disk. Checkpoint information includes the checkpoint position, SCN, location in online redo log to begin recovery, and so on. CKPT does not write data blocks to data files or redo blocks to online redo log files.
檢查點作用:
(1)定期促進DBWn程序把記憶體的髒塊寫回到資料檔案,資料庫故障時不會丟資料
(2)減少例項恢復的時間
(3)確保所有已提交的資料在一致性關閉期間會被寫入資料檔案
例項恢復時間:
指的是將資料檔案的最後一個檢查點(檢查點位置)推進到控制檔案中記錄的最新SCN所需的時間.管理員可以通過設定MTTR 目標以及調整重做日誌組的大小來控制該時間.
MTTR:
Mean Time To Repair,即平均修復時間.是指可修復產品的平均修復時間,就是從出現故障到修復中間的這段時間越短表示易恢復性越好.在資料庫中可以通過設定引數FAST_START_MTTR_TARGET(單位為秒),控制資料庫對單個例項執行崩潰恢復所花費的時間.
FAST_START_MTTR_TARGE=非0值, 啟用快速啟動檢查點功能,自動控制發檢查點速度.
FAST_START_MTTR_TARGE=0,禁用快速啟動檢查點功能.
如果重做日誌檔案的size太小,會頻繁切換日誌,即會頻繁發生檢查點,故可以增大重做日誌檔案的size減少檢查點發生頻率.
FAST_START_MTTR_TARGET如果設定的太小,為了要控制資料庫單例項的例項恢復時間，則必須頻繁發生檢查點,確保記憶體中已修改的資料塊能夠定期寫入到磁碟,故可以使用MTTR Advisor來設定推薦的值.
QUESTION 2
Identify the memory component from which memory may be allocated for:Session memory for the shared server, Buffers for I/O slaves Oracle Database Recovery Manager (RMAN) backup and restore operations
A. Large Pool
B. Redo Log Buffer
C. Database Buffer Cache
D. Program Global Area (PGA)
Correct Answer: A
Explanation/Reference:
Large Pool
The large pool is an optional memory area intended for memory allocations that are larger than is appropriate for the shared pool. The large pool can provide large memory allocations for the following:
UGA for the shared server and the Oracle XA interface (used where transactions interact with multiple databases)
Message buffers used in the parallel execution of statements
Buffers for Recovery Manager (RMAN) I/O slaves
By allocating session memory from the large pool for shared SQL, the database avoids performance overhead caused by shrinking the shared SQL cache. By allocating memory in large buffers for RMAN operations, I/O server processes, and parallel buffers, the large pool can satisfy large memory requests better than the shared pool.
QUESTION 3
You executed the following command to create a tablespace called SALES_DATA:
SQL> CREATE TABLESPACE sales_data
DATAFILE SIZE 100M
SEGMENT SPACE MANAGEMENT AUTO;
Which two statements are true about the SALES_DATA tablespace? (Choose two)
A. The database automatically determines the extent-sizing policy for the tablespace.
B. The segments are automatically shrunk when the contents are removed from them.
C. The allocation of extents within the tablespace is managed through the dictionary tables.
D. The space utilization description of the data blocks in segments is recorded in bitmap blocks.
E. The space utilization description of the data blocks in segments is managed through free lists.
Correct Answer: AD
Explanation/Reference:
段空間管理: 本地管理的表空間中的段空間管理方式可指定為:
自動:Oracle DB 使用點陣圖管理段中的空閒空間.點陣圖描述了段中每個資料塊的狀態,該狀態與可插入行的塊中的空間量有關.當資料塊中可用空間增多或減少時,點陣圖中會反映資料塊的新狀態.通過使用點陣圖,Oracle DB 可以提高管理空閒空間的自動化程度.因此,這種空間管理方式稱為"自動段空間管理(ASSM)".
手動:此方法指定要使用空閒列表來管理段中的'空閒空間.空閒列表是由一些資料塊組成的列表,這些資料塊中有可插入行的空間.由於這種管理段空間的方式需要為在表空間中建立的方案物件指定並優化PCTUSED、FREELISTS和FREELIST GROUPS儲存引數,因此這種方式稱為"手動段空間管理".支援使用此方法是為了向後相容,建議使用ASSM.
可通過dba_tablespaces檢視分割槽和段空間管理方式:
SYS@ENMOEDU> select tablespace_name,extent_management,segment_space_management from dba_tablespaces;
TABLESPACE_NAME EXTENT_MAN SEGMEN
---------------- ---------- ------
SYSTEM LOCAL MANUAL
SYSAUX LOCAL AUTO
TEMP LOCAL MANUAL
USERS LOCAL AUTO
EXAMPLE LOCAL AUTO
UNDOTBS1 LOCAL MANUAL
QUESTION 4
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
Correct Answer: BE
Explanation/Reference:
DBA一般在資料庫出現介質損壞的時候執行恢復操作.
A: 錯誤,alert日誌損壞資料庫不會丟失資料,不需要恢復.
B: 正確,表空間在作業系統改名需要執行恢復,資料庫找不到表空間對應的資料檔案.
C: 錯誤,丟失redo成員,不會丟失資料,不需要執行恢復操作.
D: 錯誤,會話異常終止不會丟失資料,不需要恢復,資料庫會釋放異常會話佔用的資源.
E: 正確,磁碟損壞會導致在該磁碟的資料檔案損壞,需要執行恢復操作.
