Book Image

Mastering PostgreSQL 15 - Fifth Edition

By : Hans-Jürgen Schönig
Book Image

Mastering PostgreSQL 15 - Fifth Edition

By: Hans-Jürgen Schönig

Overview of this book

Starting with an introduction to the newly released features of PostgreSQL 15, this updated fifth edition will help you get to grips with PostgreSQL administration and how to build dynamic database solutions for enterprise apps, including designing both physical and technical aspects of the system. You'll explore advanced PostgreSQL features, such as logical replication, database clusters, advanced indexing, and user management to manage and maintain your database. You'll then work with the PostgreSQL optimizer, configure PostgreSQL for high speed, and move from Oracle to PostgreSQL. Among the other skills that the book will help you build, you’ll cover transactions, handling recursions, working with JSON and JSONB data, and setting up a Patroni cluster. It will show you how to improve performance with query optimization. You'll also focus on managing network security and work with backups and replication while exploring useful PostgreSQL extensions that optimize the performance of large databases. By the end of this PostgreSQL book, you’ll be able to use your database to its utmost capacity by implementing advanced administrative tasks with ease.
Table of Contents (16 chapters)

Understanding the transaction log

Every modern database system provides functionality to make sure that a system can survive a crash if something goes wrong or somebody pulls the plug. This is true for filesystems and database systems alike.

PostgreSQL also provides a means to ensure that a crash cannot harm the integrity of data or the data itself. It guarantees that if the power cuts out, the system will always be able to come back on again and do its job.

The means of providing this kind of security is achieved by the Write-Ahead Log (WAL), or xlog. The idea is to not write into a data file directly but instead to write to the log first. Why is this important? Imagine that we are writing some data, as follows:

INSERT INTO data ... VALUES ('12345678');

Let’s assume that this data was written directly to the data file. If the operation fails midway, the data file would be corrupted. It might contain half-written rows, columns without index pointers, missing...