052-197(新增70题2018)

You specified extent management as local for a tablespace.

How will it affect space management in the tablespace?

A. All the extents will be of the same size.

B. Bitmap will be used to record free and allocated extents.

C. Free extents will be managed by the data dictionary tables.

D. The tablespace will be system managed and the users cannot specify the extent size.

Answer: B

Locally Managed Tablespaces

Locally managed tablespaces track all extent information in the tablespace itself by using bitmaps, resulting in the following benefits:

• Fast, concurrent space operations. Space allocations and deallocations modify locally managed resources (bitmaps stored in header files).

• Enhanced performance

• Readable standby databases are allowed, because locally managed temporary tablespaces do not generate any undo or redo.

• Space allocation is simplified, because when the AUTOALLOCATE clause is specified, the database automatically selects the appropriate extent size.

• User reliance on the data dictionary is reduced, because the necessary information is stored in file headers and bitmap blocks.

• Coalescing free extents is unnecessary for locally managed tablespaces.

All tablespaces, including the SYSTEM tablespace, can be locally managed.

The DBMS_SPACE_ADMIN package provides maintenance procedures for locally managed tablespaces.