Book Image

PostgreSQL 14 Administration Cookbook

By : Simon Riggs, Gianni Ciolli
5 (1)
Book Image

PostgreSQL 14 Administration Cookbook

5 (1)
By: Simon Riggs, Gianni Ciolli

Overview of this book

PostgreSQL is a powerful, open-source database management system with an enviable reputation for high performance and stability. With many new features in its arsenal, PostgreSQL 14 allows you to scale up your PostgreSQL infrastructure. With this book, you'll take a step-by-step, recipe-based approach to effective PostgreSQL administration. This book will get you up and running with all the latest features of PostgreSQL 14 while helping you explore the entire database ecosystem. You’ll learn how to tackle a variety of problems and pain points you may face as a database administrator such as creating tables, managing views, improving performance, and securing your database. As you make progress, the book will draw attention to important topics such as monitoring roles, validating backups, regular maintenance, and recovery of your PostgreSQL 14 database. This will help you understand roles, ensuring high availability, concurrency, and replication. Along with updated recipes, this book touches upon important areas like using generated columns, TOAST compression, PostgreSQL on the cloud, and much more. By the end of this PostgreSQL book, you’ll have gained the knowledge you need to manage your PostgreSQL 14 database efficiently, both in the cloud and on-premise.
Table of Contents (14 chapters)

Which are my biggest tables?

We've looked at getting the size of a specific table, so now it's time to widen the problem to related areas. Rather than having an absolute value for a specific table, let's look at the relative sizes.

How to do it...

The following basic query will tell us the 10 biggest tables:

SELECT quote_ident(table_schema)||'.'||quote_ident(table_name) as name 
      ,pg_relation_size(quote_ident(table_schema)
              || '.' || quote_ident(table_name)) as size
FROM information_schema.tables
WHERE table_schema NOT IN ('information_schema', 'pg_catalog')
ORDER BY size DESC
LIMIT 10;

The tables are shown in descending order of size, with at the most 10 rows displayed. In this case, we look at all the tables in all the schemas, apart from the tables in information_schema or pg_catalog, as we did in the How many tables are in the database? recipe.

How it works…

PostgreSQL provides a dedicated function, pg_relation_size, to compute the actual disk space used by a specific table or index. We just need to provide the table name. In addition to the main data files, there are other files (called forks) that can be measured by specifying an optional second argument. These include the Visibility Map (VM), the Free Space Map (FSM), and the initialization fork for unlogged objects.