1. Database Reference
  2. Dynamic Performance Views
  3. Dynamic Performance (V$) Views: V$IM_COLUMN_LEVEL to V$RULE_SET_AGGREGATE_STATS
  4. V$IM_SEGMENTS

9.2 V$IM_SEGMENTS

V$IM_SEGMENTS presents information about all the in-memory segments in the database.

Only segments that have an in-memory representation are displayed. If a segment is marked for the In-Memory Column Store (IM column store) but is not populated, no corresponding row for that segment is displayed in this view.

Column Datatype Description

OWNER

VARCHAR2(128)

User name of the segment owner

SEGMENT_NAME

VARCHAR2(128)

Name of the segment, if any

PARTITION_NAME

VARCHAR2(128)

Object partition name (set to NULL for non-partitioned objects)

SEGMENT_TYPE

VARCHAR2(18)

Type of segment:

  • TABLE

  • TABLE PARTITION

  • TABLE SUBPARTION

TABLESPACE_NAME

VARCHAR2(30)

Name of the tablespace containing the segment

INMEMORY_SIZE

NUMBER

Size of the in-memory version of the segment, in bytes

BYTES

NUMBER

Number of on-disk data bytes for the segment that could be represented in memory (no space metadata blocks)

BYTES_NOT_POPULATED

NUMBER

Size of the portion of the on-disk segment that is not populated in memory, in bytes.

POPULATE_STATUS

VARCHAR2(9)

Status of segment population:

  • STARTED: Indicates that a segment populate task is started

  • COMPLETED: Indicates that no segment populate task is pending

  • FAILED: Indicates that a segment populate task has failed

INMEMORY_PRIORITY

VARCHAR2(8)

Indicates the priority for IM column store population:

  • LOW

  • MEDIUM

  • HIGH

  • CRITICAL

  • NONE

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)

Compression level for the IM column store:

  • NO MEMCOMPRESS

  • FOR DML

  • FOR QUERY [ LOW | HIGH ]

  • FOR CAPACITY [ LOW | HIGH ]

  • AUTO

INMEMORY_SERVICE

VARCHAR2(12)

Specifies how the IM-enabled table is populated on various instances:

  • DEFAULT: Pre-Oracle Database 12c Release 2 (12.2.0.1) behavior

  • NONE: Do not populate on any instance

  • ALL: Populate on all instances

  • USER_DEFINED: Populate only on the instances on which the user-specified service is active. The service name corresponding to this is stored in the INMEMORY_SERVICE_NAME column.

INMEMORY_SERVICE_NAME

VARCHAR2(129)

Specifies the service name on which the IM-enabled table should be populated. This column has a value only when the corresponding INMEMORY_SERVICE column has a value of USER_DEFINED.

IS_EXTERNAL

VARCHAR2(5)

Indicates whether the IM segment is for an external table. Possible values:

  • TRUE: The IM segment is for an external table.

  • FALSE: The IM segment is not for an external table.

CON_ID

NUMBER

The ID of the container to which the data pertains. Possible values include:

  • 0: This value is used for rows containing data that pertain to the entire multitenant container database (CDB). This value is also used for rows in non-CDBs.

  • 1: This value is used for rows containing data that pertain to only the root

  • n: Where n is the applicable container ID for the rows containing data

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