Book Image

Redis Essentials

By : Maxwell Dayvson da Silva
Book Image

Redis Essentials

By: Maxwell Dayvson da Silva

Overview of this book

Redis is the most popular in-memory key-value data store. It's very lightweight and its data types give it an edge over the other competitors. If you need an in-memory database or a high-performance cache system that is simple to use and highly scalable, Redis is what you need. Redis Essentials is a fast-paced guide that teaches the fundamentals on data types, explains how to manage data through commands, and shares experiences from big players in the industry. We start off by explaining the basics of Redis followed by the various data types such as Strings, hashes, lists, and more. Next, Common pitfalls for various scenarios are described, followed by solutions to ensure you do not fall into common traps. After this, major differences between client implementations in PHP, Python, and Ruby are presented. Next, you will learn how to extend Redis with Lua, get to know security techniques such as basic authorization, firewall rules, and SSL encryption, and discover how to use Twemproxy, Redis Sentinel, and Redis Cluster to scale infrastructures horizontally. At the end of this book, you will be able to utilize all the essential features of Redis to optimize your project's performance.
Table of Contents (11 chapters)
5
5. Clients for Your Favorite Language (Become a Redis Polyglot)
10
Index

Transactions


A transaction in Redis is a sequence of commands executed in order and atomically. The command MULTI marks the beginning of a transaction, and the command EXEC marks its end. Any commands between the MULTI and EXEC commands are serialized and executed as an atomic operation. Redis does not serve any other client in the middle of a transaction.

All commands in a transaction are queued in the client and are only sent to the server when the EXEC command is executed. It is possible to prevent a transaction from being executed by using the DISCARD command instead of EXEC. Usually, Redis clients prevent a transaction from being sent to Redis if it contains command syntax errors.

Unlike in traditional SQL databases, transactions in Redis are not rolled back if they produce failures. Redis executes the commands in order, and if any of them fail, it proceeds to the next command. Another downside of Redis transactions is that it is not possible to make any decisions inside the transaction...