OCP-1Z0-053-V12.02-420题

420.Automatic PGA Memory Management eliminates the need to manually configure which of the

following initialization parameters? (Choose all that apply.)

A. SORT_AREA_SIZE

B. HASH_AREA_SIZE

C. BITMAP_MERGE_AREA_SIZE

D. CREATE_BITMAP_AREA_SIZE

E. PGA_AGGREGATE_TARGET

Answer: ABCD

 答案解析：

参考：http://docs.oracle.com/cd/E11882_01/server.112/e25494/memory.htm#ADMIN11208

Using Manual PGA Memory Management

Oracle Database supports manual PGA memory management, in which you manually tune SQL work areas.

In releases earlier than Oracle Database 10g, the database administrator controlled the maximum size of SQL work areas by setting the following parameters:SORT_AREA_SIZE, HASH_AREA_SIZE, BITMAP_MERGE_AREA_SIZE and CREATE_BITMAP_AREA_SIZE. Setting these parameters is difficult, because the maximum work area size is ideally selected from the data input size and the total number of work areas active in the system. These two factors vary greatly from one work area to another and from one time to another. Thus, the various *_AREA_SIZE parameters are difficult to tune under the best of circumstances.

For this reason, Oracle strongly recommends that you leave automatic PGA memory management enabled.

If you decide to tune SQL work areas manually, you must set the WORKAREA_SIZE_POLICY initialization parameter to MANUAL.

Note:

The initialization parameter WORKAREA_SIZE_POLICY is a session- and system-level parameter that can take only two values:MANUAL or AUTO. The default is AUTO. You can set PGA_AGGREGATE_TARGET, and then switch back and forth from auto to manual memory management mode. When WORKAREA_SIZE_POLICY is set to AUTO, your settings for *_AREA_SIZE parameters are ignored.