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)
1
Section 1: Getting Started
5
Section 2: Interacting with the Database
12
Section 3: Administering the Cluster
20
Section 4: Replication
23
Section 5: The PostegreSQL Ecosystem

Exploring the disk layout of PGDATA

In the previous sections, you have seen how to install PostgreSQL and connect to it, but we have not looked at the storage part of a cluster. Since the aim of PostgreSQL, as well as the aim of any relational database, is to permanently store data, the cluster needs some sort of permanent storage. In particular, PostgreSQL exploits the underlying filesystem to store its own data. All of the PostgreSQL-related stuff is contained in a directory known as PGDATA.

The PGDATA directory acts as the disk container that stores all the data of the cluster, including the users' data and cluster configuration.

The following is an example of the content of PGDATA for a running PostgreSQL 12 cluster (it looks the same for a PostgreSQL 13 instance):

$ sudo ls -1 /postgres/12
PG_VERSION
base
global
pg_commit_ts
pg_dynshmem
pg_hba.conf
pg_ident.conf
pg_logical
pg_multixact
pg_notify
pg_replslot
pg_serial
pg_snapshots
pg_stat
pg_stat_tmp
pg_subtrans
pg_tblspc
pg_twophase
pg_wal
pg_xact...