In-Memory DataBase Reference

This chapter describes initialization parameters and dynamic performance views relevant for IMCS.

In-Memory Initialization Parameters

INMEMORY_SIZE

The INMEMORY_SIZE parameter specifies the size of IMCS in a database instance. The default value is 0, which allocates no memory for IMCS.

The minimum value that can be specified as INMEMORY_SIZE is 100 MB, and the value cannot be dynamically changed while the database is running. In a TAC environment, the INMEMORY_SIZE parameter must be set to an equal value for all TAC instances.

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In-Memory Dynamic Performance Views

V$IM_COLUMN_LEVEL

V$IM_COLUMN_LEVEL presents the selective column compression levels and indicates whether a column is set as No Inmemory. There is no GV$ view for V$IM_COLUMN_LEVEL in TAC, since all TAC nodes have the same information.

Option	Description
OWNER	Name of the table owner
OBJ_NUM	Table object ID
TABLE_NAME	Table name
SEGMENT_COLUMN_ID	Segment Column Number
COLUMN_NAME	Column name
INMEMORY_COMPRESSION	In-Memory compression option specified for a column, including No Inmemory setting
CON_ID	The ID of the container to which the data pertains

V$IM_SEGMENTS

V$IM_SEGMENTS displays information about all segments existing in the In-Memory Area. You can find any information about populated segments through this view.

Option	Description
OWNER	Name of Segment Owner
SEGMENT_NAME	Name of Segment
PARTITION_NAME	Object partition name Set to NULL for non-partitioned objects
SEGMENT_TYPE	Type of Segment Table Table Partition Table Subpartition
TABLESPACE_NAME	Name of the tablespace containing the segment
INMEMORY_SIZE	Size of the in-memory version of the segment, in bytes
BYTES	Number of bytes for the segment
BYTES_NOT_POPULATED	Size of the portion of the segment that is not populated In-Memory Area, in bytes
POPULATE_STATUS	Status of segment population STARTED COMPLETED FAILED
INMEMORY_PRIORITY	Priority for segment population LOW MEDIUM HIGH CRITICAL NONE
INMEMORY_DISTRIBUTE	In-Memory DISTRIBUTE option specified for the segment AUTO BY ROWID RANGE BY PARTITION BY SUBPARTITION
INMEMORY_DUPLICATE	In-Memory DUPLICATE option specified for the segment NO DUPLICATE DUPLICATE DUPLICATE ALL
INMEMORY_COMPRESSION	In-Memory compression option specified for the segment NO MEMCOMPRESS FOR QUERY LOW FOR QUERY HIGH