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A materialized view is a database object that contains the results of a query. They are local copies of data located remotely, or are used to create summary tables based on aggregations of a table's data. Materialized views, which store data based on remote tables, are also known as snapshots. A snapshot can be redefined as a materialized view.

A materialized view in Oracle is a replica of a target master from a single point in time. The master can be either a master table at a master site or a master materialized view at a materialized view site. Whereas in multimaster, replication tables are continuously updated by other master sites, materialized views are updated from one or more masters through individual batch updates, known as a refreshes, from a single master site or master materialized view site.

Monitoring the time window between two refreshes will provide you with a fair idea of the volume of changes that materialized views have been updated with. This test reports this refresh interval.

For this test to report metrics, the database should contain at least one materialized view.

Measurement	Description	Measurement Unit	Interpretation
Interval_time	Indicates the duration of time elapsed since the materialized view was last refreshed in this Oracle database.	Minutes	When a materialized view is fast refreshed, Oracle must examine all of the changes to the master table or master materialized view since the last refresh to see if any apply to the materialized view. Therefore, if any changes were made to the master since the last refresh, then a materialized view refresh takes some time to apply the changes to the materialized view. If, however, no changes at all were made to the master since the last refresh of a materialized view, then the materialized view refresh should be very quick.