Book Image

Mastering PostgreSQL 13 - Fourth Edition

By : Hans-Jürgen Schönig
Book Image

Mastering PostgreSQL 13 - Fourth Edition

By: Hans-Jürgen Schönig

Overview of this book

Thanks to its reliability, robustness, and high performance, PostgreSQL has become one of the most advanced open source databases on the market. This updated fourth edition will help you understand PostgreSQL administration and how to build dynamic database solutions for enterprise apps with the latest release of PostgreSQL, including designing both physical and technical aspects of the system architecture with ease. Starting with an introduction to the new features in PostgreSQL 13, this book will guide you in building efficient and fault-tolerant PostgreSQL apps. You’ll explore advanced PostgreSQL features, such as logical replication, database clusters, performance tuning, advanced indexing, monitoring, 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. The book also covers transactions, locking, and indexes, and shows you how to improve performance with query optimization. You’ll also focus on how to manage 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 get the most out of your database by executing advanced administrative tasks.
Table of Contents (15 chapters)

Understanding the transaction log

Every modern database system provides functionality to make sure that the system can survive a crash in case 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 data's integrity or the data itself. It is guaranteed 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 the 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...