Creating Cluster Joins

How to:

Create a Cluster Join by Enhancing Existing Synonyms

Cluster joins enable you to create a new file structure by linking existing synonyms of two or more relational tables using the same or mixed data sources. For example, you may join a Db2 table and an Oracle table, and so on. Use cluster joins to create new views in the metadata by linking together physical tables and easily report against the new view or structure. You can create cluster joins by using the Metadata canvas Modeling View.

The Master File that is created combines the fields of the joined tables within a single file. The Access File from the combined file contains information about the actual location of the data sources and the Join information. It also shows how the tables are linked.

The total number of tables that you can add to the tool is 512 (using 511 joins), which results in a new Master File that has a maximum of 512 segments.

The Cluster Join tool enables you to create a Star Schema which consists of a fact table referencing a number of dimension tables. Optionally, you can also create a view that has more than one fact table.

Procedure: How to Create a Cluster Join by Enhancing Existing Synonyms

Use the Modeling View to enhance an existing synonym by adding a segment.

From the Projects or Data Servers area, open a synonym by double-clicking a Master File from the Master Files folder.

The Metadata canvas opens.
Click the Modeling View tab.

The Modeling View tab opens in the workspace.
Right-click a segment in the workspace and select Insert.
Insert tables (segments) through one of the methods listed:

To insert a segment from an existing synonym as child or root:
1. Select Insert, then Reference to Existing Synonym as Child or Reference to Existing Synonym as Root.
  
  The Insert Reference to Existing Synonym dialog box opens.
2. Select a synonym to be inserted and click Select.
  
  Note: Use this method if you are creating a cluster join with an existing table or synonym.
  
  Tip: Click Save As from the Modeling View File menu if you do not want to modify the original synonym.
To insert a segment via Metadata Import:
1. Select Insert, then Segment via Metadata Import. This enables you to add segments by using the Create Synonym tool. This tool creates a synonym and includes it as a segment in the synonym from which the tool was launched.
  
  Note: Use this method if you are creating a cluster join and need to use a synonym that does not exist. This option enables you to create the synonym and continue to create the cluster join.
2. When this option is selected, you are first presented with the Adapter dialog box where you can select a configured adapter connection to continue or configure a new adapter, if necessary.
To insert a segment manually:

Select Insert, then Segment Manually. This enables you to assign values to segment attribute fields.

Note: Use this method if you are coding a new Master File, as you would for a data source.

The segment is added in the Modeling View.
Right-click the join line between the segments.

Note: This option is only available when using relational tables.
Select a Join Type from the shortcut menu.

The Join Condition field automatically creates a Join if identical fields exist in both segments.

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