1Z0-062 · Question #332
Examine the command: SQL> CREATE TABLESPACE test1 DATAFILE '/u01/app/oracle/oradata/orc1/test01.dbf' SIZE 5M AUTOEXTEND ON UNIFORM; Which statement is true?
The correct answer is C. Allocated and free extents are tracked using bitmaps. The CREATE TABLESPACE command using the UNIFORM clause creates a locally managed tablespace where extent allocation is managed internally. In such tablespaces, allocated and free extents are tracked efficiently using bitmaps within the data files themselves.
Question
Examine the command:
SQL> CREATE TABLESPACE test1 DATAFILE '/u01/app/oracle/oradata/orc1/test01.dbf' SIZE 5M AUTOEXTEND ON UNIFORM; Which statement is true?
Options
- AThe data file, TEST01.DBF, can be auto extended to a maximum size of 5M.
- BThe tablespace, TEST1, can contain a maximum of one data file.
- CAllocated and free extents are tracked using bitmaps.
- DSegment free space is tracked in the data dictionary.
How the community answered
(32 responses)- A3% (1)
- B19% (6)
- C72% (23)
- D6% (2)
Why each option
The `CREATE TABLESPACE` command using the `UNIFORM` clause creates a locally managed tablespace where extent allocation is managed internally. In such tablespaces, allocated and free extents are tracked efficiently using bitmaps within the data files themselves.
The `AUTOEXTEND ON` clause allows the data file to grow beyond its initial `SIZE 5M`, potentially up to a system-defined or explicitly specified maximum size, not restricting it to 5M.
A tablespace can contain multiple data files; the `CREATE TABLESPACE` command merely specifies the initial data file, and more can be added later.
The `UNIFORM` keyword in the `CREATE TABLESPACE` command specifies a Locally Managed Tablespace (LMT) with uniform extent sizes. For LMTs, Oracle uses bitmaps stored in the data file headers to manage the allocation and deallocation of both free and allocated extents, which provides better performance than dictionary-managed tablespaces.
In locally managed tablespaces, segment free space management (Automatic Segment Space Management - ASSM) uses bitmaps within the segment headers, not the data dictionary, for tracking free space.
Concept tested: Oracle Locally Managed Tablespace extent management
Source: https://docs.oracle.com/en/database/oracle/oracle-database/19/admin/managing-tablespaces.html#GUID-0D1D691A-FC94-4286-B9C0-53D2A4B8A287
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