关于Oracle 12c 中的Heat Map

关于Oracle 12c 中的Heat Map:

以下摘自：Information Lifecycle Management (ILM), Heat Map, Automatic Data Optimization (ADO) (文档 ID 1612385.1)

Heat Map is an Oracle Database 12c feature that stores system-generated data usage statistics at the row and segment levels – information that can be used to automate the compression and movement of data in order to reduce storage costs, improve performance
and optimize Oracle Database storage. Heat Map, used in conjunction with Automatic Data Optimization can automate compression and storage policies based on the usage of the data. Segment level Heat Map tracks the time of last modification and access of tables
and partitions. Row level Heat Map shows modification times at the row level. Heat Map, once enabled, automatically collects segment and row level statistics that can be used to define compression and storage policies which will be automatically maintained
throughout the lifecycle of the data. Heat Map skips internal access done for system tasks -- automatically excluding Stats Gathering, DDLs or Table Redefinitions.

Heat Map can be enabled as:

ALTER SYSTEM SET HEAT_MAP = ON;

By default the value is OFF

The V$HEAT_MAP_SEGMENT view displays real-time segment access information. The ALL_, DBA_, and USER_HEAT_MAP_SEGMENT views display the latest segment access time for all segments visible to the user. The ALL_, DBA_, and USER_HEAT_MAP_SEG_HISTOGRAM views
display segment access information for all segments visible to the user. The DBA_HEATMAP_TOP_OBJECTS view displays heat map information for the top 1000 objects. The DBA_HEATMAP_TOP_TABLESPACES view displays heat map information for the top 100 tablespaces.