Source Qualifier transformation
Source Qualifier transformation acts as a virtual source in Informatica. When you drag a relational table or flat file in Mapping Designer, Source Qualifier transformation comes along. Source Qualifier is the point where Informatica processing actually starts. The extraction process starts from the Source Qualifier.
Note
Note that it is always recommended that the columns of Source and Source Qualifier match. Do not change the columns or their data type in the Source Qualifier. You can notice the difference in the data type in the Source Definition and Source Qualifier, which is because Informatica interprets the data in that way only.
To discuss Source Qualifier, let's take an example of the Joiner transformation mapping we created earlier.
As you can notice, there are two Source Qualifier transformations present in mapping: one for flat file and the other for relational database. You can notice that we have connected only three columns from the Source Qualifier...