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 the [previous lesson](https://www.educative.io/pageeditor/6650775272947712/6601946975698944/5904258529492992), we looked at a few commands used to insert lists into the Redis database. In this lesson, we will look at how we can modify a List present in the database.

##  `LLEN` command
The `LLEN` command is used to find the length of the list, as shown below.
>LLEN *key*

![](/api/collection/6650775272947712/6601946975698944/page/5904258529492992/image/6596823738220544)

##  `LINDEX` command
The `LINDEX` command is used to find the element at a particular index in the list.

> LINDEX *key index*

In the index below, we are fetching the value at index 1.

![](/api/collection/6650775272947712/6601946975698944/page/5904258529492992/image/5247380124336128)

> Please note that the index starts at 0.

##  `LSET` command
The `LSET` command is used to update the value at a given index.

In the example below, we have **bmw** at the $0^{th}$ index. We will change it to **mercedes** using the lset command.

> LSET *key index value*

![](/api/collection/6650775272947712/6601946975698944/page/4717576044150784/image/4757721862111232)

##  `LPUSHX`command

The `lpushx` command adds an element to the head of the list if the list exists.
>LPUSHX *key value*

In the example below, we will use the `lpushx` command for a key that does not exist, i.e., toyota. It will do nothing.

![](/api/collection/6650775272947712/6601946975698944/page/5904258529492992/image/6094898974425088)

##  `LINSERT` command
This command is useful if we need to insert an element before a particular element. Let's say, we need to add the first ten natural numbers in a list. We added them but forgot to add number 6, as shown below:

![](/api/collection/6650775272947712/6601946975698944/page/5904258529492992/image/6250503089422336)

We have forgotten to add 6, which we need to add before 5. Remember: the elements are added in reverse order in the list since we are inserting at the head.

> linsert *key before/after pivot value*

The pivot is the value before which we need to insert the number.

We will use this command to insert 6 in the list.

![](/api/collection/6650775272947712/6601946975698944/page/5904258529492992/image/5558882626699264)

In the [previous lesson](https://www.educative.io/pageeditor/6650775272947712/6601946975698944/5904258529492992), we looked at a few commands used to insert lists into the Redis database. In this lesson, we will look at how we can modify a List present in the database.

# `LLEN` command
The `LLEN` command is used to find the length of the list, as shown below.
>LLEN *key*

![](/api/collection/6650775272947712/6601946975698944/page/5904258529492992/image/6596823738220544)

# `LINDEX` command
The `LINDEX` command is used to find the element at a particular index in the list.

> LINDEX *key index*

In the index below, we are fetching the value at index 1.

![](/api/collection/6650775272947712/6601946975698944/page/5904258529492992/image/5247380124336128)

> Please note that the index starts at 0.

# `LSET` command
The `LSET` command is used to update the value at a given index.

In the example below, we have **bmw** at the $0^{th}$ index. We will change it to **mercedes** using the lset command.

> LSET *key index value*

![](/api/collection/6650775272947712/6601946975698944/page/4717576044150784/image/4757721862111232)

# `LPUSHX`command

The `lpushx` command adds an element to the head of the list if the list exists.
>LPUSHX *key value*

In the example below, we will use the `lpushx` command for a key that does not exist, i.e., toyota. It will do nothing.

![](/api/collection/6650775272947712/6601946975698944/page/5904258529492992/image/6094898974425088)

# `LINSERT` command
This command is useful if we need to insert an element before a particular element. Let's say, we need to add the first ten natural numbers in a list. We added them but forgot to add number 6, as shown below:

![](/api/collection/6650775272947712/6601946975698944/page/5904258529492992/image/6250503089422336)

We have forgotten to add 6, which we need to add before 5. Remember: the elements are added in reverse order in the list since we are inserting at the head.

> linsert *key before/after pivot value*

The pivot is the value before which we need to insert the number.

We will use this command to insert 6 in the list.

![](/api/collection/6650775272947712/6601946975698944/page/5904258529492992/image/5558882626699264)

Let’s see how we can modify the data in a List in Redis.

Let's Begin

Redis Commands

Redis Advanced Concepts

Redis Cluster

Appendix

Storing Lists in Redis: Modification Commands

`LLEN` command

`LINDEX` command

Storing Lists in Redis: Modification Commands

LLEN command

LINDEX command

`LLEN` command

`LINDEX` command