DBA_HIST_MEMORY_TARGET_ADVICE displays memory target advice history. This view contains snapshots of V$MEMORY_TARGET_ADVICE.

Column Datatype NULL Description
DBID NUMBER NOT NULL Database ID for the snapshot
INSTANCE_NUMBER NUMBER NOT NULL Instance number for the snapshot
MEMORY_SIZE NUMBER NOT NULL If the MEMORY_SIZE_FACTOR column has a value of 1, then this column shows the current size of memory, as set by the MEMORY_TARGET initialization parameter.

If the value of the MEMORY_SIZE_FACTOR column is less than or greater than 1, then this column shows a proposed memory size.

MEMORY_SIZE_FACTOR NUMBER   A multiplier for the current memory size. Possible values are 0.25, 0.5, 0.75, 1, 1.5, 1.75 and 2. This multiplier times the current memory size equals the value of the MEMORY_SIZE column.
ESTD_DB_TIME NUMBER   For current memory size (MEMORY_SIZE_FACTOR = 1), the amount of database time required to complete the current workload. For a proposed memory size, the estimated amount of database time that would be required if the MEMORY_TARGET parameter were changed to the proposed size.
ESTD_DB_TIME_FACTOR NUMBER   For a proposed memory size, ratio of estimated database time to current database time
VERSION NUMBER   Version number of this recommendation