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

In an [earlier lesson](https://www.educative.io/pageeditor/6650775272947712/6601946975698944/4717576044150784), we looked at storing lists of elements in Redis. The problem with a list is that it allows duplicate elements. If we need to add unique elements, we can use a Set instead of a List.

Redis internally uses a hash table to store the elements as a Set. The image below depicts how elements are stored in a Set. There is no particular order. The elements are stored randomly, and repetition is not allowed.





Some of the commands used to handle sets in Redis are listed below. Let’s suppose we need to maintain a list of fruits available in a grocery store. A given fruit cannot be repeated in the list.

# `SADD` command
To add an element into a set in Redis, we use the `SADD` command.
> SADD *key value*

In the example below, we are adding the fruits to Redis.

![](/api/collection/6650775272947712/6601946975698944/page/6268907158503424/image/6408155165622272)

Now we will try to add **apple** again to the set. We will receive 0 as the output of the SADD command, which means the fruit was not added.

![](/api/collection/6650775272947712/6601946975698944/page/6268907158503424/image/5381602147303424)


# `SMEMBERS` command
To see all the elements in a set, we can use the `SMEMBERS` command.

>SMEMBERS *key*

![](/api/collection/6650775272947712/6601946975698944/page/6268907158503424/image/5176702142513152)

# `SISMEMBER` command
To check if an element is present in a set, we can use the `SISMEMBER` command. If the element is present in the set then 1 will be returned. Otherwise, 0 will be returned.

>SISMEMBER *key value*

![](/api/collection/6650775272947712/6601946975698944/page/6268907158503424/image/4508727105814528)

# `SCARD` command
This command is used to find the count of members present in the set.

> SCARD *key*


![](/api/collection/6650775272947712/6601946975698944/page/6268907158503424/image/5161561632014336)

# `SDIFF` command
The `SDIFF` command is used to find the difference between two sets.

> Suppose we have two sets, i.e., S1 and S2. The difference,  $S1 - S2$, returns all those elements that are present in S1 but not in S2.

Let's create another key called **fruits1**.

![](/api/collection/6650775272947712/6601946975698944/page/6268907158503424/image/6301840082731008)

Now we will find the difference between **fruits** and **fruits1**.

![](/api/collection/6650775272947712/6601946975698944/page/6268907158503424/image/5887358558797824)












Learn about the commands to store sets in Redis database.

Let's Begin

Redis Commands

Redis Advanced Concepts

Redis Cluster

Appendix

Storing Set in Redis: Insertion Commands