Book Image

Learn PostgreSQL

By : Luca Ferrari, Enrico Pirozzi
Book Image

Learn PostgreSQL

By: Luca Ferrari, Enrico Pirozzi

Overview of this book

PostgreSQL is one of the fastest-growing open source object-relational database management systems (DBMS) in the world. As well as being easy to use, it’s scalable and highly efficient. In this book, you’ll explore PostgreSQL 12 and 13 and learn how to build database solutions using it. Complete with hands-on tutorials, this guide will teach you how to achieve the right database design required for a reliable environment. You'll learn how to install and configure a PostgreSQL server and even manage users and connections. The book then progresses to key concepts of relational databases, before taking you through the Data Definition Language (DDL) and commonly used DDL commands. To build on your skills, you’ll understand how to interact with the live cluster, create database objects, and use tools to connect to the live cluster. You’ll then get to grips with creating tables, building indexes, and designing your database schema. Later, you'll explore the Data Manipulation Language (DML) and server-side programming capabilities of PostgreSQL using PL/pgSQL, before learning how to monitor, test, and troubleshoot your database application to ensure high-performance and reliability. By the end of this book, you'll be well-versed with the Postgres database and be able to set up your own PostgreSQL instance and use it to build robust solutions.
Table of Contents (27 chapters)
Section 1: Getting Started
Section 2: Interacting with the Database
Section 3: Administering the Cluster
Section 4: Replication
Section 5: The PostegreSQL Ecosystem

Managing roles

Roles can be managed by means of three main SQL statements: CREATE ROLE to create a role from scratch, ALTER ROLE to change some role properties (for example, the login password), and DROP ROLE to remove an existing role.

In order to use the SQL statements to create new roles and then manage them, it is necessary to connect to a database in the cluster. The superuser role postgres can be used to that aim, at least initially; such a role is created when the database cluster is initialized. Using the postgres role and a template database is the most common way to create your initial roles.

PostgreSQL ships with a set of shell scripts that can be used to create, modify, and delete roles without connecting directly to the cluster. Under the hood, those scripts connect to the template database and perform the same SQL commands found in this section.

A role is identified by a string that represents the role name, or better, the account name of that role. Such a name must be...