Expression transformation is used for row wise manipulation also to perform non-aggregate calculations.
The Expression transformation accepts the row wise data, manipulates it, and passes it to the downstream transformation.
Expression Transformation Use Cases:
Expression transformation can be used to:
▹ Concatenate or split incoming field values
▹ Create new fields
▹ Insert hard coded values into a field
▹ Perform non aggregate calculations
Expression Transformation Field Types:
In Expression transformation new fields of below type can be created:
▹ Output Field
▹ Variable Field
▹ Input Macro Field
▹ Output Macro Field
Create an Output Field to perform certain operation for each record in the dataflow and pass it to the downstream transformation.
Create a Variable Field for calculations that you want to use within the transformation. The variable fields are not passed to the downstream transformations. They are usually used to hold a temporary value and can be used directly in the output fields created in the expression transformation.
Expression Transformation Example:
You can create the variable or output ports as shown in below.
Expression Transformation Field Expressions:
You can use any Informatica pre-defined functions in the expression transformation as shown in below.
Expression system Variables:
In Expression Transformation, we have predefined system variables which can be used in the transformation as shown in below.
Tips to Improve the performance of Expression Transformation:
▹ Use operators than functions.
▹ Instead of “concat()” function use “||” operator.
▹ Numerical operations are faster than string operations.
▹ Use variable ports to reduce the repetitive calculations.