Chapter 15 DBMS-Specific Features

Rebuilding join indexes for all references linked to a fact table

You can automatically generate a join index for each selected fact table and the dimension tables that it references. The rebuild process only applies to fact tables selected in the Selection tab of the Join Index Rebuild tab.

Each automatically generated join index consists of the references that link a fact table to all the dimension tables located on a single axis proceeding from the fact table.


A reference between two fact tables does not generate any join index.

A join index is constrained and can only be defined for tables that are organized in a connected tree.

Parameter Result of selection
Delete and Rebuild When selected all existing indexes are deleted before join index rebuild.
Preserve When selected, preserves all existing join indexes in the PDM.

The same feature applies to Oracle bitmap join indexes.

For more information on Oracle bitmap join indexes, see section Automatically creating bitmap join indexes through rebuilding.

Steps To rebuild join indexes for all references linked to a fact table:

  1. Select Tools→Rebuild Objects→Rebuild Join Indexes to open the Rebuild Join Indexes dialog:
  2. Click the Selection tab, and select one or more fact tables from the list:
  3. Click OK, and then Yes to confirm rebuilding of the join indexes.

    A join index is automatically generated for each fact table.

    Note   Displaying automatically generated join indexes
    Automatically generated join indexes appear in the list of join indexes. To display the list, select Model→ Join Indexes.


 

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