- Data warehousing is done; storing large quantities of data on daily or monthly basis.
- for performance, summaries are used; spl aggregate views which calculate the complex joins and calculations and store the result before query execution and stores in db.
- These summaries are objects; called MATERIALIZED VIEWS.
- Materialized views are the equivalent to a summary.
- End user-> Queries the db table-> server rewrites the query to use materiazed views-> makes it fast to run and good response time.
- Users can directly use mat. views as well instead of the Oracle server doing that internally.
- The query optimizer automatically knows how and when to use mat. views.
- optimizer checks which execution plan is better; the normal one or the one with the mat. view; and based on that; the best one is used.
- it can have as many aggregate func and joins as you want!!!! Amazing...
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