Chapter 15 Materialized Views

Abstract

Materialized view (MV) technology was introduced in Oracle Database version 7. This feature was originally called snapshots, and you can still see this nomenclature reflected in some data-dictionary structures. A materialized view allows you to execute a SQL query at a point in time and store the result set in a table (either locally or in a remote database). After the MV is initially populated, at some later point in time you can re-run the MV query and store the fresh results in the underlying table. There are two main uses for materialized views:

• Replicating of data to offload query workloads to separate reporting databases

• Improving performance of queries by periodically computing and storing the results of complex aggregations of data, which lets users query point-in-time results (of the complex queries)