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OBIEE Multiple Logical Table Sources

OBIEE Multiple Logical Table Sources

What is Logical Table Sources?

  • Logical Table Source (LTS) means Mapping between Physical and Logical Column.
  • LTS define the mappings from a single logical table to one or more physical tables.
  • A logical table can contain one or more LTS.
  • Multiple LTS means converting a snowflake schema to star schema.

Example

Multiple LTS are used to convert Snowflakes schema to Star schemas in BMM layer.

Let us say you have two dimensions − Dim_Brand and Dim_Product and one fact table FCT_Sales in the Physical layer.

Here your Dim_Brand is normalized to Dim_Product to implement Snowflakes schema. So in your Physical diagram, it would be like this −

Dim_Brand <—— Dim_Product <——- FCT_Sales

When we move these table to the BMM layer, we will create a single dimension table Dim_Product with 2 logical sources corresponding to Dim_Product and Dim_Brand. In your BMM diagram −

Dim_Brand <———– FCT_Sales


Adding multiple logical table sources to a logical table

  • In the BMM layer, expand Supermarket> D17 Product> Sources. Notice that the D17 Product logical table has one logical table source named D17 Product
OBIEE Multiple Logical Table Sources
OBIEE Multiple Logical Table Sources
  • Rename the D17 Product logical table source (not the logical table) to LTS1 Product (double click.

OBIEE Multiple Logical Table Sources

  • Double-click LTS1 Product to open the Logical Table Source dialog box.
OBIEE Multiple Logical Table Sources
OBIEE Multiple Logical Table Sources
  • Click the Column Mapping tab and notice that all logical columns map to physical columns in the same physical table: D17 Product. Make sure “Show mapped columns” is selected.
  • Click OK.

OBIEE Multiple Logical Table Sources

  • In the Physical layer, expand Supermarket >Sup_v2

OBIEE Multiple Logical Table Sources

  • Drag D1 Brand from the Physical layer to the D17 Product logical table in the BMM layer.

OBIEE Multiple Logical Table Sources

  • In the BMM layer, double-click the new D1 Brand logical table source to open the Logical Table Source dialog box.
  • Select show mapped columns and show unmapped columns

OBIEE Multiple Logical Table Sources

  • On the General tab, enter LTS2 Product Brand

OBIEE Multiple Logical Table Sources

  • Hence a single logical table now maps to two physical sources.

OBIEE Multiple Logical Table Sources


Specifying Logical Content

    • Double-click LTS1 Product to open the Logical Table Source dialog box.
    • Select Content Tab
    • Select Aggregation Content Group by Logical Level.

OBIEE Multiple Logical Table Sources

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