7 – Summary Management

This chapter discusses how materialized views could be used to precompute the results of frequently asked queries. Summary management in Oracle provides a complete framework to manage materialized views. Fast refresh and partition change tracking allows materialized views to be kept up-to-date when the warehouse gets loaded. Tools such as EXPLAIN_MVIEW and TUNE_MVIEW make it extremely simple to create and use materialized views. A summary is the precomputed result of a structured query language query. Once a summary has been created, the result of the query can be obtained from the summary. A summary can also be used to answer other related queries. To use a summary, the query has to be modified somehow to reference that summary. Choosing which summaries to create requires an understanding of the workload, i.e., which types of questions users are asking and how often the same information is being requested. Because summaries consume disk space and take time to refresh, it is important to select a few summaries that produce the most performance benefits.