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

Transaction isolation levels

In a concurrent system, you could encounter three different problems:

  • Dirty reads: A dirty read happens when the database is allowing a transaction to see work-in-progress data from other not-yet-finished transactions. In other words, data that has not been consolidated is visible to other transactions. No production-ready database allows that, and PostgreSQL is no exception: you are assured your transaction will only perceive data that has been consolidated and, in order to be consolidated, the transactions that created such data must be complete.
  • Nonrepeatable reads: An unrepeatable read happens when the same query, within the same transaction, executed multiple times, perceives a different set of data. This essentially means that the data has changed between two sequential executions of the same query in the same transaction. PostgreSQL does not allow this kind of problem by means of snapshots: every transaction can perceive the snapshot of the data available...