A materialized view is a replica of a target master from a single point in time. The concept was first introduced with Oracle7 termed as snapshot. In Oracle release 7.1.6 snapshots were enhanced to enableDMLs along with a new terminology, updatable snapshots. With Oracle8.1.6 snapshots started to be used in data warehouse environments so a new terminology materialized view was introduced to address bothdistributed and data warehouse materialized views.