Mapping variables and parameters in Informatica Mapping and session

Mapping variables and parameters in Informatica Mapping

1) Informatica Mapping Parameters:

You use mapping parameters to supply parameter values to informatica mappings. It could be values such as Batch_Key, Batch_Name etc.The value of the mapping parameters do not change for the entire execution time of a session. The mapping parameters can be defined in the mapping as shown in the screenshot below in the mapping designer.The same mapping parameters needs to be defined in the parameter file too.

For example, the parameter file would have:

$$BATCH_KEY=301

In the mapping designer, you would define the $$BATCH_KEY in the mapping and parameters window. During execution the session will associate the value 301 where it finds $$BATCH_KEY in the mapping. It might also be necessary to define the same parameter in the worflow under the variables tab.

2) Informatica Mapping Variables:

Mapping variable represents a value that can change through the session. Mapping variables can also be defined under the mapping and parameters window of the mapping designer just like parameters (shown in screenshot above). It can also be initialized using the parameter file. However the values of a variable can be changed during execution. The value of the mapping variables can be changed in an expression transformation using setvariable functions. For example:

SETVARIABLE($$BATCH_KEY, 302)  would change the value of $$BATCH_KEY to 302 during execution.

SETVARIABLE function can be used in expression, filter, router, and update strategy.Integration Service saves the value of a mapping variable to the repository at the end of each successful session run and uses that value the next time you run the session.

Postsession and presession variable assignment in session can be used to pass the value of the mapping variable to the session/workflow variables.This allows using the values of the variable at workflow level as shown in screenshot below.   

3)Informatica Session Parameters:

Session parameters represent values that can change between session runs, such as database connections or source and target files. E.g.: $DBConnectionName, $InputFileName, etc. These paramters needs to defined in the parameter file.

4)Informatica Workflow variables:

All the parameters, variables that have to be used in the workflow needs to be defined in the workflow in the window below. This can be all the mapping parameters, session parameters, etc.