Introduction to Redis List

Redis is unique and supports a structured linked list. Redis stores a structured sequence of strings and key values. Redis lists are a collection of strings sorted as an insertion order and can add components to Redis list by push mechanism to the front and back end of the list by LPUSH and RPUSH. And the user can pop the items from both the back and front end of the list by RPOP and LPOP. Redis list is used to simply order the string list by tail or head of the list.

Redis list is used to manage the structured list and the user can add the elements in the tail or head of the list. All types of strings are welcomed in the structured list. The functions that can be executed by list are standard and can be found in all programming languages. The user can add the elements by using LPUSH and RPUSH, that is back or front of the list, and can revoke items from back and front using RPOP and LPOP. The user can fetch a component from the required position by using LINDEX and some range of components can also be fetched using LRANGE.

Key Takeaways

• Redis search is used for secondary indexes.
• Redis list is used to view the string values and deploy queues and stacks.
• Redis list can build management of queues.
• The user can also insert and remove the items from the middle, or trim the entire list to the required size by eliminating from both or single end.

Redis List in Commands

There are a few commands to work on the Redis list:

• BLPOP key 1 [key 2] timeout is used to delete and fetch the first element from the blocks or list until one component is available.
• BRPOP key 1 [key 2] timeout is used to delete and fetch the last component from the blocks or list until one is available.
• BRPOPLPUSH destination source timeout is used to get value from the list, move to another list and return it again till one is available.
• LINDEX key index is used to fetch an element from the list with its index.
• LLEN key is used to print the list length.
• LPOP key is used to delete and fetch the initial list element.
• LPUSH key value 2 [value 1] is used to prepend the multiple values.
• LPUSHX key value is used to prepend any value to the list only if the list is present.
• LRANGE key stop start fetches the element range from the given list.
• LREM key value count deletes the element from the list.
• LSET key-value index fixes the value of a component in the list with its index.
• LTRIM key stop start is used to fix the element value in the list using its index.
• RPOP key is used to delete and fetch the last value in the list.
• RPOPPLPUSH destination source deletes the end element in the list, then append it to another list and returns the value.
• RPLPUSH key value 2 [value 1] is used to append multiple values to the list.
• RPUSHX key value is used to append any value to the list only if the list is present.

How to Use Redis List?

The RPUSH, LINDEX, LRANGE, LPOP commands are given below:

Redis 129.0.0.2:6378 > rpush list- key item
(integer) a
Redis 129.0.0.2:6378 > rpush list- key item 1
(integer) b
Redis 129.0.0.2:6378 > rpush list- key item
(integer) c

When the push items are done to a list, the command gives the present length of the list.

Redis 129.0.0.2:6378 > l range list-key 0 -1

a) “item”

b) “item 1”

c) “item”

The user can fetch the whole list by giving a range of start index as 0 and last index as -1.

Redis 129.0.0.2:6378 > lindex list-key b

“item 1”

The user can fetch the individual item in the list using LINDEX.

Redis 129.0.0.2:6378 > lpop list-key a

“item”

Redis 127.0.0.1:6379> lrange list-key 0 -1

a) “item 1”

b) “item”

If the element is popped from the list, then it will be no longer available.

Redis List in Database

Multiple operations can be performed with the list, and apart from that, Redis is an effective platform for managing multiple problems. The user can also insert and remove the items from the middle, or trim the entire list to the required size by eliminating from both or single end. In Redis, both the database and cache are a bit complicated. Every layer in data has different scalability, from optimizing the functions at different ends to infrastructure modularity.

It removes the unwanted part and decreases the count of moving parts according to the preferred latency. Though the infrastructure provisioning is rapid, it requires standard latency in a few components, either in the database or the association made between the items. Moving into a unified data store removes all the transverse in internal network connections. In end, developing an application with a unified data store needs only a single interface programming configuration.

FAQ

Given below are the FAQs mentioned:

Q1. Can we save a list in Redis?

Answer: Yes, Redis reads the element from left to right and the user can add a new list to the head using the LPUSH command or in the tail by using the RPUSH command. To create a new list, both LPUSH and RPUSH are used.

Q2. Can Redis be used as a database?

Answer: Redis is used as the multi-modeled primary database that allows to build of advanced featured applications with low latency and can also build microservices-based architecture on top of the Redis.

Q3. Can Redis list save objects?

Answer: It follows an object storing process and everything is saved in key-value pair format. Those keys must be unique and save the object as a string format. But as a good practice, the elements are saved in binary array format.

Conclusion

So the developers have to understand the advantages and importance of a single database instead of a cache and database which also save mental cost in terms of context switching in the development phase.

Recommended Articles

This is a guide to Redis List. Here we discuss the introduction, redis list in commands and database, FAQ respectively. You may also have a look at the following articles to learn more –

1. Redis Get All Keys
2. Redis GUI
3. Redis Pubsub
4. Redis Version

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