Talend tMap Join Model Explained

Thanks for all the good feedback on my last blog on tLogCatcher. This blog will cover how Talend tMap component performs multiple joins and filtering functions.

We will use the above (Figure 1) data set as an example. There are 3 separate CSV files that store Student, Subject and Enrolment information.
In Figure 2, you can see from the process that the Enrolment data is the main data while the Student and Subject data will be used as the lookup data.

Inner Join Example

If we use Inner Join as the Join Model for the Subject and Student data, the Enrolment records that do not have relationship with Subject and Student table will be filtered. You can see the result in Figure 4.


Left Outer Join Example

If we change the Join Model of Student data to Left Outer Join. It will allow the Student table to perform Left Join with Enrolment table. The output will like Figure 6.