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)

Working on groups of rows


Until now, you have been working on individual rows. There are a lot of operations that work on the dataset as a whole. You just learned to sort the dataset, which is a starting point to implement a list of many other operations. The first and one of the most used in this category is the aggregation of data.

Aggregating data

Suppose that you have a list of daily temperatures in a given country over a year. You may want to know the overall average temperature, the average temperature by region, or the coldest day in the year. In this section, you will learn how to solve these calculations with PDI, specifically with the Group by step.

The Group by step allows you to create groups of rows and calculate new fields over these groups. To understand how to do the aggregations, let's explain it by example. We will continue using the sales Transformation from the first section of the chapter. Now the objective will be as follows—for each pair product line/product code, perform...