Table of Contents

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  1. Preface
  2. Working with Transformations
  3. Aggregator Transformation
  4. Custom Transformation
  5. Custom Transformation Functions
  6. Data Masking Transformation
  7. Data Masking Examples
  8. Expression Transformation
  9. External Procedure Transformation
  10. Filter Transformation
  11. HTTP Transformation
  12. Identity Resolution Transformation
  13. Java Transformation
  14. Java Transformation API Reference
  15. Java Expressions
  16. Java Transformation Example
  17. Joiner Transformation
  18. Lookup Transformation
  19. Lookup Caches
  20. Dynamic Lookup Cache
  21. Normalizer Transformation
  22. Rank Transformation
  23. Router Transformation
  24. Sequence Generator Transformation
  25. Sorter Transformation
  26. Source Qualifier Transformation
  27. SQL Transformation
  28. Using the SQL Transformation in a Mapping
  29. Stored Procedure Transformation
  30. Transaction Control Transformation
  31. Union Transformation
  32. Unstructured Data Transformation
  33. Update Strategy Transformation
  34. XML Transformations

Transformation Guide

Transformation Guide

Unconnected Lookups

Unconnected Lookups

An unconnected Lookup transformation is a Lookup transformation that is not connected to a source or target in the mapping. Call the lookup with a :LKP expression in a transformation that allows expressions.
A common use for unconnected Lookup transformations is to update slowly changing dimension tables. For more information about slowly changing dimension tables, visit the Informatica Knowledge Base at http://mysupport.informatica.com.
The syntax for the lookup expression is
:LKP lookup_transformation_name(argument, argument, ...)
The order in which you list each argument must match the order of the lookup conditions in the Lookup transformation. The Lookup transformation returns the result of the query through the Lookup transformation return port. The transformation that calls the lookup receives the lookup result value in the port that contains the :LKP expression. If the lookup query fails to return a value, the port receives a null value.
When you perform an unconnected lookup, you can perform the same lookup multiple times in a mapping. You can test the results of the lookup in another expression and filter rows based on the results.
When you run a mapping that contains an unconnected Lookup transformation, the Integration Service performs the following steps:
  1. An unconnected Lookup transformation receives input values from the result of a :LKP expression in another transformation, such as an Aggregator transformation, Expression transformation, or Update Strategy transformation.
  2. The Integration Service queries the lookup source or cache based on the lookup ports and condition in the Lookup transformation.
  3. The Integration Service returns a value through the return port of the Lookup transformation.
  4. The Integration Service passes the return value to the port that contains the :LKP expression.

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