MongoDB vs Redis

So, you have decided that you are going for a NoSQL solution for your project. However, there are several NoSQL options available, and they all can be very different from each other. Two of the most popular options are MongoDB and Redis. They both offer important properties, such as speed and data organization. However, these two databases differ greatly from each other. Depending on the need and condition, either MongoDB or Redis can be more suitable.

So, what are the differences between MongoDB and Redis? When and why should you use MongoDB? When and why should you use Redis? Below, we will see the comparisons between MongoDB and Redis. Continue reading!


MongoDB is a free, open-source and cross-platform document-oriented database. Rather than using the regular fields and records of relational databases, MongoDB uses JSON-like documents and schemas, thus it is classified as a NoSQL database. It was initially released in 2009 by MongoDB Inc. under the GNU Affero General Public License and the Apache License. It is written in C, C++, and JavaScript, and is compatible with major operating systems such as Windows, Linux, OS X, Solaris, and FreeBSD. There is no need to worry about programming accessibility because MongoDB has official drivers for various programming languages and development environments. There are also many unofficial, community-driven drivers for multiple programming languages and frameworks.

On the other hand, Redis is essentially a key-value store.Redis actually stands for “Remote Dictionary Server”. It is an in-memory, cross-platform database that implements a networked in-memory key-value store with optional durability. Just like MongoDB, Redis is also an open-source software project. It is mainly developed by Salvatore Sanfilippo under the sponsor of Redis Labs. Redis is very flexible; it supports various data structures such as strings, sets, lists, maps, bitmaps, hyperloglogs, and spatial indexes. It is written in ANSI C. Many programming languages already come with Redis bindings, such as C, C++, C#, Objective-C, Common Lisp, Java, JavaScript, Perl, PHP, Python, Ruby, R, D, ActionScript, Dart, Haxe, Go, Racket, Rust, Scala, Haskell, Smalltalk, and Tcl.

The Advantages of MongoDB

The first advantage that you can expect MongoDB in comparison to Redis is that it is much easier to learn. As a document store, MongoDB is not difficult to learn, especially if you already have some background in database or object-oriented programming. In the development realm, MongoDB implements the BSON data format, which is similar to JSON. It has a hierarchical data structure in every document, and each document may have subdocuments. Due to the relative simplicity, MongoDB is also a great choice if you or your team don’t have much time or just don’t want to learn on a steep learning curve. The structure of MongoDB is very intuitive and easy to understand. Redis, on the other hand, is quite more complex. If you are just about to learn Redis, be prepared to face a steep learning curve. (See also : MongoDB vs Cassandra)

The second advantage of MongoDB is that it is more efficient for storing and querying very large datasets, especially if these datasets grow on a regular basis. MongoDB excels at scaling continuously growing datasets, at the same time making the process easy and convenient for the database admins and developers.

The Disadvantages of MongoDB

One notable disadvantage of MongoDB is that it is not as fast as Redis when handling consistent (not growing) datasets. Of course, this is because MongoDB stores its databases in the storage, not the memory. In addition, it is not as flexible as Redis; it does not different data structures.

The Advantages of Redis

You may have read several articles that Redis can actually be much faster than MongoDB when handling huge datasets. Redis actually has much higher write and read speeds if given the right environment. So, what is the right environment for Redis? Redis would be very suitable if your database will just stay the same over time. If your database has a predictable size and the database will not grow (at least not so much), Redis can greatly optimize your database on the sector of lookup speed. As mentioned above, Redis places the database in the memory, allowing the execution of high-performance caching and extremely quick data locating.

There is another way for Redis to enhance your database performance, which is by organizing your data as a key-value store. If you have a known key to search a specific record in the database, the lookup process can be incredibly quick. Thus, applications that process data in real-time can run very quickly if they run on Redis.

The other reason why Redis is incredibly popular among developers is because of its ability to use more complex data structures, such as scalars, lists, sets, hashes, etc. It can be very flexible for different needs and conditions. Since these data structures are similarly named in many programming languages, they help to make the learning curve somewhat easier for people already familiar with them.

The Disadvantages of Redis

Redis cannot handle growing datasets very well because it places its databases in the memory. Hence, growing datasets will eat up the memory. Also, Redis is great if you can take advantage of the key-value system; but, if you still require a lot of querying, Redis would be a lot more work for the developers, considering that the data might be stored in specialized data structures. Finally, as mentioned above, Redis can be more difficult to learn by beginners.

- Document store- Key-value store
- Relatively easier to learn- Relatively more difficult to learn
- Suitable for scaling growing datasets- Suitable for handling a fairly consistent, predictable database size
- Better performance in handling lots of queries- Much faster data retrieval if the usage of a known key is possible


MongoDB and Redis are two different NoSQL databases suited for different purposes. MongoDB is a document store, and is a great choice for scaling growing datasets. If your project requires lots of querying, MongoDB is also a more suitable choice. MongoDB is relatively easy to learn. Meanwhile, if your project works with a fairly consistent and predictable database size, and you will be able to use a known key for data retrieval, Redis is the way to go. Redis can deliver much faster performance for such case. Thus, Redis is also suitable for real-time reports and real-time analytics.

Leave a Reply