Gain insights into Redis's capabilities as a database, cache, and message broker. Delve into commands, transactions, and clustering. Explore flexibility, security, and data structure support with Redis.

Redis.tar.gz

Redis is an open-source, in-memory data structure store used as a database, cache, and message broker. Unlike Memcached, it supports multiple data types, giving a lot of flexibility to the user. Redis is easy to configure and provides clustering support to store data in multiple servers.

In this course, you will learn about the various commands that you can use to store different types of data structures in Redis. Some of those commands include utility, insertion, and modification commands.

You will also become familiar with different aspects of Redis, such as transactions, security, partitioning, and clustering. In all, this is your go-to guide to Redis.

Complete Guide to Redis

Previously, we discussed how to store sets in the Redis database. The elements in the set are not stored in any specific order. If we need to store the elements in sorted order, we can use sorted sets, also known as **ZSets**, in Redis.

Now, the important thing to note is how the element will be sorted. Each element should be assigned a *score* before it is inserted into a sorted set. The Redis database sorts the elements in ascending order of this *score*.

The image below shows how elements are stored in **ZSets**. We have stored a set of all the countries, sorted based on their freedom of speech index.



> The freedom of speech values are randomly taken in the examples and do not reflect the actual values.

Let's look at some of the commands used to handle sorted sets in the Redis database.

# `ZADD` command
This command is used to add elements to the sorted set in the Redis database. Here is the syntax of this command:

>ZADD *key score value ..*

In the example below, we are adding countries to the Redis database based on their freedom of speech index.

![](/api/collection/6650775272947712/6601946975698944/page/5388523877171200/image/6525075302907904)

The same element cannot be inserted twice in a sorted set as all the elements are unique. But it is possible to add multiple different elements having the same score. When multiple elements have the same score, they are ordered lexicographically.

# `ZRANGE` command
This command is for fetching all the elements for a particular key. If we need to fetch all the elements in the sorted set, we can provide -1 in the end field as shown below.

>ZRANGE *key start end*

This command shows the values but doesn't display the score of each value.

![](/api/collection/6650775272947712/6601946975698944/page/5388523877171200/image/6079653841207296)

# `ZRANGEBYSCORE` command
This command is for fetching the elements in a particular range of *scores*.

>ZRANGEBYSCORE *key start end*


![](/api/collection/6650775272947712/6601946975698944/page/5388523877171200/image/5969079286890496)

# `ZCARD` command
To get the number of elements in the sorted set, `ZCARD` is used. The syntax of this command is:

> ZCARD *key*

![](/api/collection/6650775272947712/6601946975698944/page/5388523877171200/image/5134055654817792)


# `ZCOUNT` command
This command is used to find the number of elements within a certain range of scores. Let's say we need to find all the countries where the freedom of speech index is less than 100.

>ZCOUNT *key min max*

![](/api/collection/6650775272947712/6601946975698944/page/5388523877171200/image/5018155236720640)




Let’s look at the commands used to store sorted Sets in Redis.

Let's Begin

Redis Commands

Redis Advanced Concepts

Redis Cluster

Appendix

Storing Sorted Set in Redis: Insertion Commands