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Index Techniques   «Prev  Next»
Lesson 9

BitMapped Indexes Conclusion

The main points of this module include:
  1. Bitmapped indexes are binary arrays rather than B-tree structures.
  2. The STAR hint was developed to aid in large n-way table joins in data warehouses.
  3. The STAR transformation method is used when bitmapped indexes are defined on a FACT table.
  4. Concatenated indexes are very useful in cases where the multiple WHERE conditions are commonly found in SQL queries.
  5. Function-based indexes are used to provide alternative representations to existing columns.

Glossary terms discussed in this module

Here are the terms from this module that may be new to you:
  1. n-way table joins
  2. STAR Transformation
Now that we know some advanced indexing techniques, we are ready to explore the Oracle database for Web applications.

What is a Dimension?

A dimension is a structure that categorizes data in order to enable end users to answer business questions. Commonly used dimensions are Customer, Product, and Time. For example, each store of a video chain might gather and store data regarding sales and rentals of video tapes at the check-out counter. The video chain management can build a data warehouse to analyze the sales of its products across all stores over time and help answer questions such as:
  1. What is the effect of promoting one product on the sale of a related product that is not promoted?
  2. What are the product sales before and after the promotion?
The data in the video chain's data warehouse system has two important components:
  1. dimensions and
  2. facts.
The dimensions are products, locations (stores), promotions, and time. One approach for identifying your dimensions is to review your reference tables, such as a product table that contains everything about a product, or a store table containing all information about a store. The facts are sales (units sold or rented) and profits. A data warehouse contains facts about the sales of each product at each store on a daily basis.

Advanced Execution Plan Techniques - Quiz

To complete this module, click the Quiz link below below to check your knowledge of Oracle8 index tuning options.
Advanced Execution Plan Techniques - Quiz