I Questions

Post date: 13-Jul-2010 11:23:25

What are the different Lookup methods used in Informatica?

Connected transformation is connected to other transformations or directly to target table in the mapping. An unconnected transformation is not connected to other transformations in the mapping. It is called within another transformation, and returns a value to that transformation. Connected lookup receives input values directly from mapping pipeline whereas UnConnected lookup receives values from: LKP expression from another transformation. Connected lookup returns multiple columns from the same row whereas UnConnected lookup has one return port and returns one column from each row. Connected lookup supports user-defined default values whereas UnConnected lookup does not support user defined values.

Connected Lookups : -

A connected Lookup transformation is part of the mapping data flow. With connected lookups, you can have multiple return values. That is, you can pass multiple values from the same row in the lookup table out of the Lookup transformation.

Common uses for connected lookups include:

=> Finding a name based on a number ex. Finding a Dname based on deptno

=> Finding a value based on a range of dates

=> Finding a value based on multiple conditions

Unconnected Lookups : -

An unconnected Lookup transformation exists separate from the data flow in the mapping. You write an expression using the :LKP reference qualifier to call the lookup within another transformation.

Some common uses for unconnected lookups include:

=> Testing the results of a lookup in an expression

=> Filtering records based on the lookup results

=> Marking records for update based on the result of a lookup (for example, updating slowly changing dimension tables)

=> Calling the same lookup multiple times in one mapping