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)

Improving speed using clustered tables

In this section, you will learn about the power of correlation and clustered tables. What is this about? Imagine that you want to read a whole area of data. This might be a certain time range, a block, some IDs, and so on.

The runtime of these queries will vary depending on the amount of data and the physical arrangement of data on the disk, so even if you are running queries that return the same number of rows, two systems might not provide the answer within the same time span, as the physical disk layout might make a difference.

Here is an example:

test=# EXPLAIN (analyze true, buffers true, timing true)
    SELECT *
    FROM  t_test
    WHERE id < 10000;
                           QUERY PLAN
-----------------------------------...