Step 1: When you create a new connection, for example as shown here in Connect To hadoop article, you will get to Preview Screen.
Step 2: On preview screen, select the column you want to perform join and click on down arrow to select "Join data with another table" under the transformation section.
Step 3: You will be up with a pop-up which gives you the various join operations over the column with another dataset :
- Left Join
- Right Join
- Inner Join
- Outer Join
Step 4: After successful selection of your join type, you need to select the datasource from the dropdown on the right and corresponding to which you get the columns of the external joined datasource and you need to select the foreign key on it.
Step 5: Click on Apply to perform the join operation and you get the columns from the joined dataset according to the join operation chosen on the right of the existing dataset columns.