Book Image

Mastering PostgreSQL 11 - Second Edition

By : Hans-Jürgen Schönig
Book Image

Mastering PostgreSQL 11 - Second Edition

By: Hans-Jürgen Schönig

Overview of this book

This second edition of Mastering PostgreSQL 11 helps you build dynamic database solutions for enterprise applications using the latest release of PostgreSQL, which enables database analysts to design both the physical and technical aspects of the system architecture with ease. This book begins with an introduction to the newly released features in PostgreSQL 11 to help you build efficient and fault-tolerant PostgreSQL applications. You’ll examine all of the advanced aspects of PostgreSQL in detail, including logical replication, database clusters, performance tuning, monitoring, and user management. You will also work with the PostgreSQL optimizer, configuring PostgreSQL for high speed, and see how to move from Oracle to PostgreSQL. As you progress through the chapters, you will cover transactions, locking, indexes, and optimizing queries to improve performance. Additionally, you’ll learn to manage network security and explore backups and replications, while understanding the useful extensions of PostgreSQL so that you can optimize the speed and performance of large databases. By the end of this book, you will be able to use your database to its utmost capacity by implementing advanced administrative tasks with ease.
Table of Contents (15 chapters)
Free Chapter
1
PostgreSQL Overview

Understanding transaction isolation levels

Up until now, you have seen how to handle locking, as well as some basic concurrency. In this section, you will learn about transaction isolation. To me, this is one of the most neglected topics in modern software development. Only a small fraction of software developers are actually aware of this issue, which in turn leads to mind-boggling bugs.

Here is an example of what can happen:

Transaction 1

Transaction 2

BEGIN;

SELECT sum(balance) FROM t_account;

User will see 300

BEGIN;

INSERT INTO t_account (balance) VALUES (100);

COMMIT;

SELECT sum(balance) FROM t_account;

User will see 400

COMMIT;

Most users would actually expect the first transaction to always return 300, regardless of the second transaction. However, this isn't true. By default, PostgreSQL runs in the READ COMMITTED...