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Oracle

1Z0-052 · Question #147

You executed the following command to create a tablespace called SALES_DATA: SQL> CREATE TABLESPACE sales_data DATAFILE SIZE 100M SEGMENT SPACE MANAGEMENT AUTO; Which two statements are true about…

The correct answer is A. The database automatically determines the extent-sizing policy for the tablespace. D. The space utilization description of the data blocks in segments is recorded in bitmap blocks. A tablespace created with default settings and SEGMENT SPACE MANAGEMENT AUTO is locally managed with automatic extent sizing, using bitmap blocks to track free space within segments.

Managing Database Storage Structures

Question

You executed the following command to create a tablespace called SALES_DATA:

SQL> CREATE TABLESPACE sales_data DATAFILE SIZE 100M SEGMENT SPACE MANAGEMENT AUTO; Which two statements are true about the SALES_DATA tablespace? (Choose two)

Options

  • AThe database automatically determines the extent-sizing policy for the tablespace.
  • BThe segments are automatically shrunk when the contents are removed from them.
  • CThe allocation of extents within the tablespace is managed through the dictionary tables.
  • DThe space utilization description of the data blocks in segments is recorded in bitmap blocks.
  • EThe space utilization description of the data blocks in segments is managed through free lists.

How the community answered

(33 responses)
  • A
    88% (29)
  • B
    3% (1)
  • C
    6% (2)
  • E
    3% (1)

Why each option

A tablespace created with default settings and SEGMENT SPACE MANAGEMENT AUTO is locally managed with automatic extent sizing, using bitmap blocks to track free space within segments.

AThe database automatically determines the extent-sizing policy for the tablespace.Correct

Because no EXTENT MANAGEMENT clause was specified, Oracle defaults to a locally managed tablespace with AUTOALLOCATE extent sizing, meaning Oracle automatically determines the size of each new extent allocated to growing segments.

BThe segments are automatically shrunk when the contents are removed from them.

SEGMENT SPACE MANAGEMENT AUTO only changes how free space is tracked within segments using bitmaps; it does not automatically shrink segments when data is deleted - an explicit ALTER TABLE ... SHRINK SPACE command is required for that.

CThe allocation of extents within the tablespace is managed through the dictionary tables.

Dictionary-managed tablespaces record extent allocations in data dictionary tables such as UET$ and FET$; this tablespace defaults to locally managed, which stores extent metadata in bitmaps within the tablespace itself.

DThe space utilization description of the data blocks in segments is recorded in bitmap blocks.Correct

The SEGMENT SPACE MANAGEMENT AUTO clause causes Oracle to use bitmap blocks inside each segment to record which data blocks are full, partially full, or empty, replacing the older free list mechanism for tracking space utilization.

EThe space utilization description of the data blocks in segments is managed through free lists.

Free lists are the space management mechanism used when SEGMENT SPACE MANAGEMENT MANUAL is specified; since AUTO was chosen, bitmap blocks replace free lists for tracking block-level space utilization.

Concept tested: Locally managed tablespace with automatic segment space management

Source: https://docs.oracle.com/en/database/oracle/oracle-database/19/admin/managing-tablespaces.html

Topics

#tablespace creation#ASSM#bitmap blocks#extent management

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