Oracle® DBA Guide to Data Warehousing and Star Schemas

Use Materialized Views

As for aggregates, you should always implement them as materialized views, period. First, no matter what business intelligence tool your end-users select, query rewrites can be accomplished and are desirable. Second, regardless of which aggregation method you implement from the previous section, they all will work equally well against a materialized view (since it's nothing more than a locally replicated table). There are no downsides to implementing aggregates as materialized views, therefore you should always do so. And for those of you who already have a data warehouse built, go back and create materialized views on your pre-existing aggregate tables. This way, you too can get query rewrites even though you're not using ...