Book Image

Learn PostgreSQL - Second Edition

By : Luca Ferrari, Enrico Pirozzi
1 (2)
Book Image

Learn PostgreSQL - Second Edition

1 (2)
By: Luca Ferrari, Enrico Pirozzi

Overview of this book

The latest edition of this PostgreSQL book will help you to start using PostgreSQL from absolute scratch, helping you to quickly understand the internal workings of the database. With a structured approach and practical examples, go on a journey that covers the basics, from SQL statements and how to run server-side programs, to configuring, managing, securing, and optimizing database performance. This new edition will not only help you get to grips with all the recent changes within the PostgreSQL ecosystem but will also dig deeper into concepts like partitioning and replication with a fresh set of examples. The book is also equipped with Docker images for each chapter which makes the learning experience faster and easier. Starting with the absolute basics of databases, the book sails through to advanced concepts like window functions, logging, auditing, extending the database, configuration, partitioning, and replication. It will also help you seamlessly migrate your existing database system to PostgreSQL and contains a dedicated chapter on disaster recovery. Each chapter ends with practice questions to test your learning at regular intervals. By the end of this book, you will be able to install, configure, manage, and develop applications against a PostgreSQL database.
Table of Contents (22 chapters)
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Index

How PostgreSQL handles persistency and consistency: WALs

In the previous sections, you have seen how to interact with transactions and, most notably, how PostgreSQL executes every statement within a transaction, either explicitly or implicitly.

PostgreSQL does, internally, very complex work to ensure that consolidated data in storage reflects the status of the committed transactions. In other words, data can be considered consolidated only if the transaction that produced (or modified) it has been successfully committed. But this also means that, once a transaction has been successfully committed, its data is “safe” on storage, no matter what happens in the future: if a transaction is reported to be successful, its data must be made persistent, even if the database or the whole system crashes.

PostgreSQL manages transactions and data consolidations by means of WALs. This section introduces you to the concept of WALs and their use within PostgreSQL.

WALs

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