Until now, you worked with a single stream of data. When you did calculations or created conditions to compare fields, you only involved fields of your stream. Usually, this is not enough, and you need data from other sources. In this section, you will learn how to look up data outside your stream.
Suppose that you have a list of people along with their nationalities, and you want to find out the language that they speak. This is a typical case where you have to look for information in another source of data, your main stream is the dataset with people information, and you need a secondary stream with information about the languages. This secondary stream is where we will look for new information. In PDI, we do that with the Stream lookup step.
To explain how to use this step, we will implement the proposed exercise where we will read a list of people and find out the languages that people on the list speak:
- Create a new Transformation...