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Oracle9i Discoverer Administrator Administration Guide
Version 9.0.2

Part Number A90881-02
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15
Creating summary folders manually

Creating summary folders manually

This chapter explains how you create summary folders manually using Discoverer Administrator (i.e. instead of using Automated Summary Management), and contains the following topics:

What is manual summary folder creation?

Manual summary folder creation is the process of creating summary folders yourself, instead of using Discoverer's Automated Summary Management (ASM) functionality (for more information, see Chapter 14, "Managing summary folders"). You might choose to create summary folders yourself if you want to:

You choose whether to create summary folders using ASM or manually in the first step of the Summary Wizard. To create summary folders manually you select the option I want to specify the summaries myself and complete one of the following tasks:

For information about summary folders and how Discoverer creates and maintains them automatically see Chapter 14, "Managing summary folders".

What are the prerequisites for creating summary folders manually in Discoverer?

To create summary folders, the following requirements must be met:

Notes

What are summary combinations?

Summary combinations are groupings of items that make up a summary folder. A summary combination maps directly to a summary table or materialized view in the database. Discoverer creates summary tables or materialized views based on the summary combinations you create. Each summary combination defines a different way of combining two or more items in a summary folder. If a Discoverer Plus user executes a query with a combination of items that closely matches those specified in a particular combination, the query will be run against a summary table or materialized view instead of the detail data.

You can define as many combinations as you need for each summary folder using the Summary Wizard.

Figure 15-1 The relationship between summary combinations, summary folders and summary tables/materialized views


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Text description of the illustration sumcomb.gif

If you create multiple summary combinations, Discoverer (where possible) builds the higher level combinations (i.e. combinations with a greater number of items) using the lower level combinations (i.e. combinations with fewer items). This improves performance because:

For example, if we have two summary combinations in a summary folder where the first combination is month, region and revenue and the second combination is year, region and revenue. Discoverer aggregates the data for the revenue by month and region by accessing the detail data directly. Discoverer then uses data aggregated for the first combination to aggregate the data for the second combination, saving both processing and cpu overhead.

Note: Summary combinations are only available when Discoverer manages the refresh of a summary folder. When Discoverer uses external summary tables, summary combinations are not available.

What to consider when defining summary combinations?

There are three things to consider when defining summary combinations:

The key to good summary folder design is to create the most appropriate summary combinations for the pattern of system usage.

Typically you will want queries that are run most often to run the most quickly, even if this requires more database space. Similarly, it is usually desirable for queries that run less frequently to use less database space, even if this means the queries run more slowly.

When creating summary combinations, look for:

For example, the columns of the two summary tables EUL4_SUM200801 and EUL4_SUM200802 below are mapped to appropriate items in the Sales Fact folder.

Figure 15-2 Sample summary tables and joins to fact and dimension tables


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Text description of the illustration sumtab4.gif

Key to the figure above:


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