Book Image

PostgreSQL 10 Administration Cookbook - Fourth Edition

By : Simon Riggs, Gianni Ciolli
Book Image

PostgreSQL 10 Administration Cookbook - Fourth Edition

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 10 allows users to scale up their PostgreSQL infrastructure. This book takes a step-by-step, recipe-based approach to effective PostgreSQL administration. Throughout this book, you will be introduced to these new features such as logical replication, native table partitioning, additional query parallelism, and much more. You will learn how to tackle a variety of problems that are basically the pain points for any database administrator - from creating tables to managing views, from improving performance to securing your database. More importantly, the book pays special attention to topics such as monitoring roles, backup, and recovery of your PostgreSQL 10 database, ensuring high availability, concurrency, and replication. By the end of this book, you will know everything you need to know to be the go-to PostgreSQL expert in your organization.
Table of Contents (14 chapters)

Adding a constraint without checking existing rows

A table constraint is a guarantee that must be satisfied by all the rows in the table. Therefore, adding a constraint to a table is a two-phase procedure—first, the constraint is created, and then all the existing rows are checked. Both happen in the same transaction, and the table cannot be accessed in the meantime. The constraint becomes visible after the check, yielding perfect consistency, which is usually the desired behavior—at the expense of availability, which is not that great.

This recipe demonstrates another case—how to enforce a constraint on future transactions only, without checking existing rows. This may be desirable in some specific cases, such as the following two:

  • Enabling the constraint on newer rows of a large table that cannot remain unavailable for a long time
  • Enforcing the constraint...