Understanding the Mapping Wizards - Informatica

The Designer provides two mapping wizards to help you create mappings quickly and easily. Both wizards are designed to create mappings for loading and maintaining star schemas, a series of dimensions related to a central fact table. You can, however, use the generated mappings to load other types of targets.

You choose a different wizard and different options in each wizard based on the type of target you want to load and the way you want to handle historical data in the target:

  • Getting Started Wizard. Creates mappings to load static fact and dimension tables and slowly growing dimension tables.
  • Slowly Changing Dimensions Wizard. Creates mappings to load slowly changing dimension tables based on the amount of historical dimension data you want to keep and the method you choose to handle historical dimension data.

After using a mapping wizard, you can edit the generated mapping to further customize it.

Using the Getting Started Wizard

The Getting Started Wizard creates mappings to load static fact and dimension tables and slowly growing dimension tables.

The Getting Started Wizard can create two types of mappings:

  • Pass through. Loads a static fact or dimension table by inserting all rows. Use this mapping when you want to drop all existing data from the table before loading new data.
  • Slowly growing target. Loads a slowly growing fact or dimension table by inserting new rows. Use this mapping to load new data when existing data does not require updates.

The following table describes the getting started mapping types:

getting started mapping types

Using the Slowly Changing Dimensions Wizard

The Slowly Changing Dimensions Wizard creates mappings to load slowly changing dimension tables:

  • Type 1 Dimension mapping. Loads a slowly changing dimension table by inserting new dimensions and overwriting existing dimensions. Use this mapping when you do not want a history of previous dimension data.
  • Type 2 Dimension/Version Data mapping. Loads a slowly changing dimension table by inserting new and changed dimensions using a version number and incremented primary key to track changes. Use this mapping when you want to keep a full history of dimension data and to track the progression of changes.
  • Type 2 Dimension/Flag Current mapping. Loads a slowly changing dimension table by inserting new and changed dimensions using a flag to mark current dimension data and an incremented primary key to track changes. Use this mapping when you want to keep a full history of dimension data, tracking the progression of changes while flagging only the current dimension.
  • Type 2 Dimension/Effective Date Range mapping. Loads a slowly changing dimension table by inserting new and changed dimensions using a date range to define current dimension data. Use this mapping when you want to keep a full history of dimension data, tracking changes with an effective date range.
  • Type 3 Dimension mapping. Loads a slowly changing dimension table by inserting new dimensions and updating values in existing dimensions. Use this mapping when you want to keep the current and previous dimension values in the dimension table.

The following table describes the slowly changing dimension mapping types:

slowly changing dimension mapping types

Choosing Sources for the Mappings

Use the following sources with a mapping wizard:

  • Flat file
  • Relational
  • Application
  • Shortcut to a flat file, relational, or Application sources

You cannot use COBOL or XML sources with the mapping wizards.

When you select a source for a mapping, the mapping wizards display all available sources by source name. The Designer can optionally display sources and target definitions by business name, rather than source and target name. Even when this option is selected, mapping wizards display sources by source name.

The Mapping Wizard cannot import a source when a column name uses an SQL keyword. When the Mapping Wizard encounters an SQL keyword used as a column name, it prompts you to choose another source. If you want to use a source with a column using an SQL keyword, create the mapping in the Mapping Designer.

The mapping wizards also complete the following based on the selected source:

  • Use the source name to name the source qualifier as follows: SQ_SourceName for file or relational sources, or ASQ_SourceName for Application sources.
  • Create port names based on source column names.

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