OCP-1Z0-053-V12.02-155题

155.Observe the structure of the table employees: The table contains 8475 records.

One of the employees wants to know the names of all employees of the company. For this, he fires the

following query:

SELECT * FROM EMPLOYEES ORDER BY emp_fname;

Since the operation performed on executing the query cannot fit into memory, it requires disk space to

complete the operation. Which of the following types of segments will Oracle allocate to complete the

operation and to provide the required result?

A. Rollback segment

B. Temporary segment

C. Data segment

D. Index segment

Answer: B

答案解析：

参考：http://docs.oracle.com/cd/E11882_01/server.112/e40540/logical.htm#CNCPT1072

Temporary Segments

When processing a query, Oracle Database often requires temporary workspace for intermediate stages of SQL statement execution. Typical operations that may require atemporary segment include sorting,hashing, and merging bitmaps. While creating an index, Oracle Database also places index segments into temporary segments and then converts them into permanent segments when the index is complete.

Oracle Database does not create a temporary segment if an operation can be performed in memory. However, if memory use is not possible, then the database automatically allocates a temporary segment on disk.