Redis vs. MongoDB: How to differ and which one to choose?

Enterprise Solutions, Technology

Choosing the right database for your application is not an easy task. You have a variety of options in the market. There’s no real formula that you can follow. Still, there are a couple of things you need to keep in mind while choosing the database for your application. And in this post, we will discuss about the two most popular NoSQL databases: Redis( Remote Dictionary server) (in-memory) and MongoDB (Percona memory storage engine).

What is Redis?

Redis (Remote Dictionary Server) is an open-source Database with a Key-Value storage engine. It is a caching and in-memory storage system, which is a way to store specific pieces of data in memory. It stores all sorts of data in a structured frame, from database results to the actual SQL query, to ad hoc pieces. It’s commonly used as a memory caching system and a distributed data shared memory server. Since the data resides mainly in memory, which provides this system with excellent response times in the information retrieval, it is written in ANSI C.

Redis also offers a framework for building an in-memory application that is, at the same time, versatile and scalable.

Key Features:

  1. It is very Flexible.
  2. No scheme and column required.
  3. Very fast, can perform around 110k set per second and 81k GETS per second.
  4. Rich data support.
  5. Command level atomic operation.
  6. It can be used as a backend to store result by Message Broker system using celery.
  7. It supports arbitrary data storage that allows storing key and value pairs of large size.
  8. It has its hashing mechanism called Redis Hashing.
  9. Data Replication is possible with Redis.
  10. Single Threaded event loop model that optimally utilizes the CPU, therefore, optimize the speed.

What is MongoDB?


MongoDB is an exceptional NoSQL Database with open-source cross-platform document-oriented database program. It uses a document-oriented database model that supports various forms of data. It is one of the numerous nonrelational database technologies that arose under the NoSQL banner for big data applications and other processing jobs involving data that doesn’t fit well in a rigid relational model. It is suggestive of the fact that MongoDB databases go beyond the limitations of SQL and traditional relational database management systems (RDBMS) to offer high scalability and high performance.

Key Features:

  1. It offers a database platform that can run smoothly even when the load is high.
  2. Documents (objects) can easily be mapped with programming language data types.
  3. Embedded documents and arrays reduce the need for joins.
  4. Dynamic schema makes polymorphic feature easier.
  5. It supports ad hoc queries such as field and range queries.
  6. Embedding makes reads and writes fast.
  7. With indexes can include keys from documents and arrays.
  8. It is also widely used as an efficient file storage system that can store files across multiple servers while using a load balancing feature.
  9. High Performance
  10. Replicated servers with automatic master failover.

Comparison on the basis of-

1. Speed

If we compare Redis vs. MongoDB on the basis of the speed, Mongo Db leads with a margin. MongoDB is quite easy to use, and its structure is more straightforward than Redis. On the other hand, while the fragmented code in Redis takes more time to process, it provides higher latency throughputs which gives it more speed over MongoDB. So we can conclude that Mongo DB is faster for low latency throughput, but if you are working on higher latency throughputs, Redis is ideal. 

2. Performance

Redis has a cache layer, which gives a better response time. It is preferable in case of multiple loads and performs better with a single core than MongoDB even though Redis is single-threaded. Most of the time, Mongo DB’s memory becomes CPU-bound, which brings down the performance as compared to the cache memory of Redis. But due to cache memory, Redis tends to consume more storage than MongoDB to execute the same set of operations.

3. Scaling

Mongodb outshines Redis in terms of scalability. As Redis consumes more RAM due to the cache memory for processing, this limits its scalability, whereas Mongodb requires less storage space. Therefore high scalability is achievable in MangoDB as compared to Redis.

4. Storage and Memory

Redis is a key-value store, and it keeps the data in RAM so it can get to it as quickly as possible. Each piece of data (a record) is retrieved based on a single key. The dataset is supposed to stay small enough to fit in RAM. On the other hand, MongoDB is a document store. A document is a mixed record with the elements inside separated using method. Files in MongoDB are written to the disk and are often retrieved from it. Records are indexable, meaning there is more than one way to find the record you are looking for. Redis has an advantage in terms of memory comparison.

5. Flexibility

Based on flexibility, MongoDB fares better than Redis. Mongo DB uses traditional database paradigms (queries, indexes, tables) and applies them over a flexible document store. Things like index optimization and keys (which will be familiar to existing developers) are easily translated over to MongoDB, making it a favorite for developers looking to take advantage of schema-less databases’ flexibility, but want to continue using existing tools.

6. Caching

Caching is the most widely used performance enhancing concept throughout the field of computing. MongoDB is a database solution while Redis is the combination of advanced data structure and cache memory. It is typical to implement Redis is not efficient in large scale cloud deployments as compared to MongoDB  which is more efficient for implementing large cloud deployment.If your entire dataset fits into a single server then you can go for Redis.


Redis MongoDB
Performance Effective for varying loads More Effective for Single Loads
Caching Typical to implement in large scale cloud deployments Can easily deploy setup even in the large cloud deployments.
Speed Faster in higher latency throughputs Faster in lower latency throughputs
Storage and Memory Key Value store gives edge Data is stored in document form which can be modified.
Flexibility Less flexible in database paradigm More Flexible queries, indexes, tables.
Scalability Scalability less due to higher Ram storage Higher Scalability due to less storage

Based on the above key points, you can easily differentiate between both compound-bound databases. MongoDB is more favorable on parameters like Caching, Scaling, and flexibility. On the other hand, Redis has the edge over Speed, Memory, and Performance parameters. Redis & MongoDB are widely used on many platforms worldwide based on the preference of the requirement of the above factors.