Oracle 1Z0-054 問題集

質問 1：
You are working as a DBA for a DSS system, on which applications primarily perform large sequential I/Os. The company wants to upgrade the storage used by the database to faster hard disks. What other factors would you consider before giving the go-ahead for the new hard disks? (Choose all that apply.)
A. the capacity of the I/O channel that connects the server to the storage array
B. the sizing of buffer cache to meet the faster data access
C. the sizing of PGA to meet the faster data access
D. the time it takes for a submitted I/O request to be serviced by the storage
正解：A,D

質問 2：
Examine the following information from the AWR report: Top 5 Timed Events ~~~~~~~~~~~~~~~~~~ % Total Event Waits Time (s) Call Time
CPU time 559 88.80 log file parallel write 2,181 28 4.42 SQL*Net more data from client 516,611 27 4.24 db file parallel write 13,383 13 2.04 db file sequential read 563 2 .27 Which could cause waits on the db file sequential read event?
A. too large a database buffer cache
B. toomany index range scans occurring which refers to blocks not in the database buffer cache
C. too many full table scans
D. too many waits occurring while reading multiple blocks synchronously
正解：B

質問 3：
You find that the OS utilization is over 40% in your database server. Examine the following set of performance monitoring-related activities:
1.Investigate the operating system for network transfers, paging, and swapping.
2.Check the SQL and the transactions submitting the SQL for optimal execution.
3.Investigate the top SQL by CPU utilization.
4.Consider rescheduling some work to off-peak hours.
5.Check whether there are any nondatabase jobs consuming CPU time on the machine. What is the correct sequence in which the above activities should be performed to diagnose and reduce potential performance issues?
A. 2,4,5,3,1
B. 1,2,3,4,5
C. 1,5,3,2,4
D. 4,5,3,1,2
正解：C

質問 4：
You identified a SQL statement with SQL ID 9g485acn2n30m, which is expensive on the
resources. To view the execution plan for the statement, you executed the following command:
SQL> SELECT * FROM TABLE(dbms_xplan.display_cursor('9g485acn2n30m',1));
What would this command accomplish?
A. It formats and displays the contents of the execution plan but does not guarantee that the same execution plan would be executed.
B. It formats and displays the contents of the execution plan for the cursor with the SQL_ID '9g485acn2n30m' from the DBA_HIST_SQL_PLAN view.
C. It formats and displays the contents of the execution plan for the cursor with the SQL_ID '9g485acn2n30m' from the library cache.
D. It formats and displays the contents of the execution plan but does not guarantee accuracy if the SQL statement has bind variables.
正解：C

質問 5：
View the Exhibit and examine portions of two ASH reports generated for the same time period. The second report was generated after the ASH data is flushed to disk.Why is the sample count reduced in the second report?

A. because the shared pool size is not enough to hold ASH information.
B. because the samples have been filtered from ASH buffer.
C. because a portion of the ASH rolling buffer has been overwritten.
D. because the AWR is not able to store all the samples.
正解：B

質問 6：
View the Exhibit and examine the content of the V$SGA_RESIZE_OPS view.

You executed the following command to increase the size of the Large Pool:
SQL> ALTER SYSTEM SET large_pool_size=8M;
System altered.
Which component would shrink to increase the size of the Large Pool?
A. Default Buffer Cache
B. KEEP Buffer Cache
C. the Java Pool
D. the Shared Pool
正解：A

質問 7：
You are working on a decision support system (DSS). The index is available on the COUNTRY_ID column of the CUSTOMERS table.View the Exhibit and examine the parameter settings and the query execution plan.

Why is the query using a full table scan instead of an index scan?
A. because the histogram statistics for the COUNTRY_ID column are not updated
B. because the DB_FILE_MULTIBLOCK_READ_COUNT initialization parameter is set to a higher value
C. because the index statistics for the index on the COUNTRY_ID column are not current
D. because the optimizer predicts that most of the blocks in the tableare accessed. Therefore, it uses a full table scan, even though indexes are available.
正解：D