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

Exploring physical backups

A physical backup is a low-level backup that's taken during the normal operations of the database cluster. Here, low-level means that the backup is somehow performed "externally" inside the backup cluster; that is, at the filesystem level.
As you already know from Chapter 10, Users, Roles, and Database Security, the database cluster requires both the data files contained in PGDATA/base and the write-ahead logs (WALs) contained in PGDATA/wal, as well as a few other files, to make the cluster work properly. The main concept, however, is that the data files and the WALs can make the cluster self-healing and recover from a crash. Hence, a physical backup performs a copy of all the cluster files and then, when the restore is required, it simulates a database crash and makes the cluster self-heal with the WALs in place.

The reason why physical backups are important is that they allow us to effectively clone a cluster, starting from the files it is...