Instead of the entire company accessing a single database server, user load is distributed across multiple database servers. If one of your goals is to reduce network loads, then you can use materialized views to distribute your corporate database to regional sites. You can use materialized views to achieve one or more of the following goals: 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. Therefore, if any changes where made to the master since the last refresh, then a materialized view refresh takes some time to apply the changes to the materialized view. 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.
Text description of the illustration rep81072.gif Figure 3-1 Materialized View Connected to a Single Master Site
The arrows in Figure 3-1 represent database links. 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, as illustrated in Figure 3-1. The master can be either a master table at a master site or a master materialized view at a materialized view site. Oracle9i Data Warehousing Guide to learn more about materialized views for data warehousingĪ materialized view is a replica of a target master from a single point in time.