Book Image

Learning Pentaho Data Integration 8 CE - Third Edition

Book Image

Learning Pentaho Data Integration 8 CE - Third Edition

Overview of this book

Pentaho Data Integration(PDI) is an intuitive and graphical environment packed with drag-and-drop design and powerful Extract-Tranform-Load (ETL) capabilities. This book shows and explains the new interactive features of Spoon, the revamped look and feel, and the newest features of the tool including transformations and jobs Executors and the invaluable Metadata Injection capability. We begin with the installation of PDI software and then move on to cover all the key PDI concepts. Each of the chapter introduces new features, enabling you to gradually get practicing with the tool. First, you will learn to do all kind of data manipulation and work with simple plain files. Then, the book teaches you how you can work with relational databases inside PDI. Moreover, you will be given a primer on data warehouse concepts and you will learn how to load data in a data warehouse. During the course of this book, you will be familiarized with its intuitive, graphical and drag-and-drop design environment. By the end of this book, you will learn everything you need to know in order to meet your data manipulation requirements. Besides, your will be given best practices and advises for designing and deploying your projects.
Table of Contents (17 chapters)

Executing transformations in an iterative way


If you have to execute the same Transformation several times, once for each row or subset of your data, you can do it by iterating the execution. This section shows you how to do it.

Using Transformation executors

The Transformation Executor is a PDI step that allows you to execute a Transformation several times simulating a loop. The executor receives a dataset, and then executes the Transformation once for each row or a set of rows of the incoming dataset.

To understand how this works, we will build a very simple example. The inner Transformation, that is, the Transformation that will be executed iteratively, will receive a row with a student code and a student name and will create a file with some message for the student. The main Transformation will generate a list of students and then it will execute the inner Transformation once for every student, that is, once for every row.

Let's start by creating the Transformation that will run iteratively...