Book Image

Learn PostgreSQL - Second Edition

By : Luca Ferrari, Enrico Pirozzi
1 (2)
Book Image

Learn PostgreSQL - Second Edition

1 (2)
By: Luca Ferrari, Enrico Pirozzi

Overview of this book

The latest edition of this PostgreSQL book will help you to start using PostgreSQL from absolute scratch, helping you to quickly understand the internal workings of the database. With a structured approach and practical examples, go on a journey that covers the basics, from SQL statements and how to run server-side programs, to configuring, managing, securing, and optimizing database performance. This new edition will not only help you get to grips with all the recent changes within the PostgreSQL ecosystem but will also dig deeper into concepts like partitioning and replication with a fresh set of examples. The book is also equipped with Docker images for each chapter which makes the learning experience faster and easier. Starting with the absolute basics of databases, the book sails through to advanced concepts like window functions, logging, auditing, extending the database, configuration, partitioning, and replication. It will also help you seamlessly migrate your existing database system to PostgreSQL and contains a dedicated chapter on disaster recovery. Each chapter ends with practice questions to test your learning at regular intervals. By the end of this book, you will be able to install, configure, manage, and develop applications against a PostgreSQL database.
Table of Contents (22 chapters)
20
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21
Index

RLS

In the previous part of the chapter, you saw the permission mechanism by which PostgreSQL allows roles (both users and groups) to access different objects within the database and the data contained in those objects.

In particular, with regard to tables, you learned how to restrict access to just a specific column list within the tabular data.

PostgreSQL provides another interesting mechanism to restrict access to tabular data: RLS. The idea is that RLS decides which tuples the role can have access to, either in read or write mode. Therefore, if the column-based permissions provide a way of limiting the vertical shape of the tabular data, RLS provides a way to restrict the horizontal shape of the data itself.

When is it appropriate to use RLS? Imagine you have a table that contains data related to users, and you don’t want your users to be able to tamper with other users’ data. In such a case, restricting the access of every user to just their own tuples...