15 In-Memory Views

This topic describes data dictionary and dynamic performance views related to the In-Memory Column Store (IM column store).

Table 15-1 In-Memory Views

Initialization Parameter Description

DBA_EXPRESSION_STATISTICS

Provides expression usage tracking statistics for all the tables in the database.

DBA_EXTERNAL_TABLES

Describes all external tables in the database. The INMEMORY column indicates whether the table is enabled for INMEMORY, and INMEMORY_COMPRESSION indicates the compression level.

Related views include ALL_XTERNAL_PART_TABLES, ALL_XTERNAL_TAB_PARTITIONS, and ALL_XTERNAL_TAB_SUBPARTITIONS.

DBA_FEATURE_USAGE_STATISTICS

Displays information about database feature usage statistics. When the IM column store is accessed, the NAME column shows In-Memory Column Store.

DBA_HEAT_MAP_SEGMENT

Displays the latest segment access time for all segments. The timestamps in the view are coarse with a granularity of a day reflecting the flush times of the heat map.

DBA_INMEMORY_AIMTASKS

Describes the status of tasks created by Automatic In-Memory.

DBA_INMEMORY_AIMTASKDETAILS

Describes the object and action taken by Automatic In-Memory.

DBA_ILMDATAMOVEMENTPOLICIES

Contains information specific to data movement-related attributes of an Automatic Data Optimization policy in a database.

DBA_IM_EXPRESSIONS

Describes the IM expressions, which have the column prefix SYS_IME, that have the INMEMORY attribute.

DBA_JOINGROUPS

Describes join groups in the database. A join group is a user-created object that lists two columns that can be meaningfully joined.

DBA_SEGMENTS

Describes the storage allocated for all segments in the database. Several columns, including INMEMORY and INMEMORY_PRIORITY, describe In-Memory attributes of the segment.

DBA_TABLES

Indicates which tables have the INMEMORY attribute set (the INMEMORY column is ENABLED) or not set (DISABLED).

V$ACTIVE_SESSION_HISTORY

Displays sampled session activity. Several columns, including INMEMORY_QUERY and INMEMORY_POPULATE, describe session activity relating to the In-Memory Column Store at the time of sampling.

V$HEAT_MAP_SEGMENT

Displays real-time segment access information.

V$IM_COLUMN_LEVEL

Presents the selective column compression levels that are defined using the INMEMORY clause of the CREATE TABLE statement. SYS_IME hidden virtual columns are not shown in this view.

V$IM_SEGMENTS

Presents information about all In-Memory segments in the database. Only segments that have an In-Memory representation are displayed. If a segment is marked for the IM column store but is not populated, the view does not contain a corresponding row for this segment.

V$INMEMORY_AREA

Displays information about the space allocation inside the In-Memory Area.

V$INMEMORY_FASTSTART_AREA

Provides information about the In-Memory FastStart (IM FastStart) area.

V$SGA

Displays the size of the In-Memory Area.