6.353 DBA_SEGMENTS

DBA_SEGMENTS describes the storage allocated for all segments in the database.

Related View

USER_SEGMENTS describes the storage allocated for the segments owned by the current user's objects. This view does not display the OWNER, HEADER_FILE, HEADER_BLOCK, or RELATIVE_FNO columns.

Column Datatype NULL Description

OWNER

VARCHAR2(128)

Username of the segment owner

SEGMENT_NAME

VARCHAR2(128)

Name, if any, of the segment

PARTITION_NAME

VARCHAR2(128)

Object Partition Name (Set to NULL for nonpartitioned objects)

SEGMENT_TYPE

VARCHAR2(18)

Type of segment:

  • NESTED TABLE

  • TABLE

  • TABLE PARTITION

  • CLUSTER

  • LOBINDEX

  • INDEX

  • INDEX PARTITION

  • LOBSEGMENT

  • TABLE SUBPARTITION

  • INDEX SUBPARTITION

  • LOB PARTITION

  • LOB SUBPARTITION

  • ROLLBACK

  • TYPE2 UNDO

  • DEFERRED ROLLBACK

  • TEMPORARY

  • CACHE

  • SPACE HEADER

  • UNDEFINED

SEGMENT_SUBTYPE

VARCHAR2(10)

Subtype of LOB segment: SECUREFILE, ASSM, MSSM, and NULL

TABLESPACE_NAME

VARCHAR2(30)

Name of the tablespace containing the segment

HEADER_FILE

NUMBER

Absolute file number of the data file containing the segment header

HEADER_BLOCK

NUMBER

ID of the block containing the segment header

BYTES

NUMBER

Size, in bytes, of the segment

BLOCKS

NUMBER

Size, in Oracle blocks, of the segment

EXTENTS

NUMBER

Number of extents allocated to the segment

INITIAL_EXTENT

NUMBER

Size in bytes requested for the initial extent of the segment at create time. (Oracle rounds the extent size to multiples of 5 blocks if the requested size is greater than 5 blocks.)

NEXT_EXTENT

NUMBER

Size in bytes of the next extent to be allocated to the segment

MIN_EXTENTS

NUMBER

Minimum number of extents allowed in the segment

MAX_EXTENTS

NUMBER

Maximum number of extents allowed in the segment

MAX_SIZE

NUMBER

Maximum number of blocks allowed in the segment

RETENTION

VARCHAR2(7)

Retention option for SECUREFILE segment

MINRETENTION

NUMBER

Minimum retention duration for SECUREFILE segment

PCT_INCREASE

NUMBER

Percent by which to increase the size of the next extent to be allocated

FREELISTS

NUMBER

Number of process freelists allocated to this segment

FREELIST_GROUPS

NUMBER

Number of freelist groups allocated to this segment

RELATIVE_FNO

NUMBER

Relative file number of the segment header

BUFFER_POOL

VARCHAR2(7)

Buffer pool to be used for segment blocks:

  • DEFAULT

  • KEEP

  • RECYCLE

FLASH_CACHE

VARCHAR2(7)

Database Smart Flash Cache hint to be used for segment blocks:

  • DEFAULT

  • KEEP

  • NONE

Solaris and Oracle Linux functionality only.

CELL_FLASH_CACHE

VARCHAR2(7)

Cell flash cache hint to be used for segment blocks:

  • DEFAULT

  • KEEP

  • NONE

See Also: Oracle Exadata Storage Server Software documentation for more information

INMEMORY

VARCHAR2(8)

Indicates whether the In-Memory Column Store (IM column store) is enabled (ENABLED) or disabled (DISABLED) for this segment

INMEMORY_PRIORITY

VARCHAR2(8)

Indicates the priority for In-Memory Column Store (IM column store) population:

  • LOW

  • MEDIUM

  • HIGH

  • CRITICAL

  • NONE

  • NULL

INMEMORY_DISTRIBUTE

VARCHAR2(15)

Indicates how the IM column store is distributed in an Oracle Real Application Clusters (Oracle RAC) environment:

  • AUTO

  • BY ROWID RANGE

  • BY PARTITION

  • BY SUBPARTITION

INMEMORY_DUPLICATE

VARCHAR2(13)

Indicates the duplicate setting for the IM column store in an Oracle RAC environment:

  • NO DUPLICATE

  • DUPLICATE

  • DUPLICATE ALL

INMEMORY_COMPRESSION

VARCHAR2(17)

Indicates the compression level for the IM column store:

  • NO MEMCOMPRESS

  • FOR DML

  • FOR QUERY [ LOW | HIGH ]

  • FOR CAPACITY [ LOW | HIGH ]

  • AUTO

  • NULL

CELLMEMORYFoot 1Foot 1

VARCHAR2(24)

The value for columnar compression in the storage cell flash cache. Possible values:

  • ENABLED: Oracle Exadata Storage will decide automatically whether to cache in columnar form

  • DISABLED: Oracle Exadata Storage is prevented from caching in columnar form

  • NO CACHECOMPRESS: Oracle Exadata Storage will cache in HCC format (no recompression)

  • FOR QUERY: Oracle Exadata Storage will recompress and cache in INMEMORY query high format

  • FOR CAPACITY: Oracle Exadata Storage will recompress and cache in INMEMORY capacity low format

Footnote 1

This column is intended for use with Oracle Exadata

See Also:

"USER_SEGMENTS"