Redis Hashes are maps between the string fields and the string values. Hence, they are the perfect data type to represent objects.

In Redis, every hash can store up to more than 4 billion field-value pairs.

Example

redis 127.0.0.1:6379> HMSET tutorialspoint name "redis tutorial"
description "redis basic commands for caching" likes 20 visitors 23000
OK
redis 127.0.0.1:6379> HGETALL tutorialspoint
1) "name"
2) "redis tutorial"
3) "description"
4) "redis basic commands for caching"
5) "likes"
6) "20"
7) "visitors"
8) "23000"

In the above example, we have set Redis tutorials detail (name, description, likes, visitors) in hash named ‘tutorialspoint’.

Redis Hash Commands

Following table lists some basic commands related to hash.

Redis Sorted Sets are similar to Redis Sets with the unique feature of values stored in a set. The difference is, every member of a Sorted Set is associated with a score, that is used in order to take the sorted set ordered, from the smallest to the greatest score.

In Redis sorted set, add, remove, and test for the existence of members in O(1) (constant time regardless of the number of elements contained inside the set). Maximum length of a list is 2³² – 1 elements (4294967295, more than 4 billion of elements per set).

Example

redis 127.0.0.1:6379> ZADD tutorials 1 redis
(integer) 1
redis 127.0.0.1:6379> ZADD tutorials 2 mongodb
(integer) 1
redis 127.0.0.1:6379> ZADD tutorials 3 mysql
(integer) 1
redis 127.0.0.1:6379> ZADD tutorials 3 mysql
(integer) 0
redis 127.0.0.1:6379> ZADD tutorials 4 mysql
(integer) 0
redis 127.0.0.1:6379> ZRANGE tutorials 0 10 WITHSCORES
1) "redis"
2) "1"
3) "mongodb"
4) "2"
5) "mysql"
6) "4"

In the above example, three values are inserted with its score in Redis sorted set named ‘tutorials’ by the command ZADD.

Redis Sorted Sets Commands

Following table lists some basic commands related to sorted sets.

Redis Sets are an unordered collection of unique strings. Unique means sets does not allow repetition of data in a key.

In Redis set add, remove, and test for the existence of members in O(1) (constant time regardless of the number of elements contained inside the Set). The maximum length of a list is 2³² – 1 elements (4294967295, more than 4 billion of elements per set).

Example

redis 127.0.0.1:6379> SADD tutorials redis
(integer) 1
redis 127.0.0.1:6379> SADD tutorials mongodb
(integer) 1
redis 127.0.0.1:6379> SADD tutorials mysql
(integer) 1
redis 127.0.0.1:6379> SADD tutorials mysql
(integer) 0
redis 127.0.0.1:6379> SMEMBERS tutorials
1) "mysql"
2) "mongodb"
3) "redis"

In the above example, three values are inserted in Redis set named ‘tutorials’ by the command SADD.

Redis Sets Commands

Following table lists some basic commands related to sets.

Redis HyperLogLog is an algorithm that uses randomization in order to provide an approximation of the number of unique elements in a set using just a constant, and small amount of memory.

HyperLogLog provides a very good approximation of the cardinality of a set even using a very small amount of memory around 12 kbytes per key with a standard error of 0.81%. There is no limit to the number of items you can count, unless you approach 2⁶⁴ items.

Example

Following example explains how Redis HyperLogLog works.

redis 127.0.0.1:6379> PFADD tutorials "redis"
1) (integer) 1
redis 127.0.0.1:6379> PFADD tutorials "mongodb"
1) (integer) 1
redis 127.0.0.1:6379> PFADD tutorials "mysql"
1) (integer) 1
redis 127.0.0.1:6379> PFCOUNT tutorials
(integer) 3

Redis HyperLogLog Commands

Following table lists some basic commands related to Redis HyperLogLog.

Redis Pub/Sub implements the messaging system where the senders (in redis terminology called publishers) sends the messages while the receivers (subscribers) receive them. The link by which the messages are transferred is called channel.

In Redis, a client can subscribe any number of channels.

Example

Following example explains how publish subscriber concept works. In the following example, one client subscribes a channel named ‘redisChat’.

redis 127.0.0.1:6379> SUBSCRIBE redisChat
Reading messages... (press Ctrl-C to quit)
1) "subscribe"
2) "redisChat"
3) (integer) 1

Now, two clients are publishing the messages on the same channel named ‘redisChat’ and the above subscribed client is receiving messages.

redis 127.0.0.1:6379> PUBLISH redisChat "Redis is a great caching technique"
(integer) 1
redis 127.0.0.1:6379> PUBLISH redisChat "Learn redis by tutorials point"
(integer) 1
1) "message"
2) "redisChat"
3) "Redis is a great caching technique"
1) "message"
2) "redisChat"
3) "Learn redis by tutorials point"

Redis PubSub Commands

Following table lists some basic commands related to Redis Pub/Sub.

Redis connection commands are basically used to manage client connections with Redis server.

Example

Following example explains how a client authenticates itself to Redis server and checks whether the server is running or not.

redis 127.0.0.1:6379> AUTH "password"
OK
redis 127.0.0.1:6379> PING
PONG

Redis Connection Commands

Following table lists some basic commands related to Redis connections.

Redis database can be secured, such that any client making a connection needs to authenticate before executing a command. To secure Redis, you need to set the password in the config file.

Example

Following example shows the steps to secure your Redis instance.

127.0.0.1:6379> CONFIG get requirepass
1) "requirepass"
2) ""

By default, this property is blank, which means no password is set for this instance. You can change this property by executing the following command.

127.0.0.1:6379> CONFIG set requirepass "tutorialspoint"
OK
127.0.0.1:6379> CONFIG get requirepass
1) "requirepass"
2) "tutorialspoint"

After setting the password, if any client runs the command without authentication, then (error) NOAUTH Authentication required. error will return. Hence, the client needs to use AUTH command to authenticate himself.

Syntax

Following is the basic syntax of AUTH command.

127.0.0.1:6379> AUTH password

Example

127.0.0.1:6379> AUTH "tutorialspoint"
OK
127.0.0.1:6379> SET mykey "Test value"
OK
127.0.0.1:6379> GET mykey
"Test value"

In this chapter, you will learn about the environmental setup for Redis.

Install Redis on Ubuntu

To install Redis on Ubuntu, go to the terminal and type the following commands −

$sudo apt-get update
$sudo apt-get install redis-server

This will install Redis on your machine.

Start Redis

$redis-server

Check If Redis is Working

$redis-cli

This will open a redis prompt.

redis 127.0.0.1:6379>

In the above prompt, 127.0.0.1 is your machine”s IP address and 6379 is the port on which Redis server is running. Now type the following PING command.

redis 127.0.0.1:6379> ping
PONG

This shows that Redis is successfully installed on your machine.

Install Redis Desktop Manager on Ubuntu

To install Redis desktop manager on Ubuntu, just download the package from

Open the downloaded package and install it.

Redis desktop manager will give you UI to manage your Redis keys and data.

Redis scripting is used to evaluate scripts using the Lua interpreter. It is built into Redis starting from version 2.6.0. The command used for scripting is EVAL command.

Syntax

Following is the basic syntax of EVAL command.

redis 127.0.0.1:6379> EVAL script numkeys key [key ...] arg [arg ...]

Example

Following example explains how Redis scripting works.

redis 127.0.0.1:6379> EVAL "return {KEYS[1],KEYS[2],ARGV[1],ARGV[2]}" 2 key1
key2 first second
1) "key1"
2) "key2"
3) "first"
4) "second"

Redis Scripting Commands

Following table lists some basic commands related to Redis Scripting.