Which database is best? MongoDB vs. Redis

MongoDB vs. Redis: How do these two powerful NoSQL databases, both with different focuses, compare? While MongoDB is primarily designed for large volumes of data, Redis impresses with its speed. The two systems can also be combined.

MongoDB: Scalable and flexible

MongoDB, derived from the English term “humongous”, is one of the best-known and most popular NoSQL systems in the world. The database was developed in 2009 by the company 10gen (now MongoDB Inc.) to store and securely manage large and diverse amounts of data. The system is characterized in particular by its high horizontal scalability and the associated flexibility that comes with it. MongoDB is written in C++ and is distributed under the Server Side Public License as an open-source database management system, which is continually being further developed and which offers additional proprietary versions.

Redis: The NoSQL solution with speed

The two solutions in this MongoDB vs. Redis comparison were released in the same year despite their many differences. Redis, whose name is derived from “REmote DIctionary Server”, was released in 2009. The in-memory database was programmed in ANSI C by Salvatore Sanfilippo. Like MongoDB, it is open source (under the 3-clause BSD license) and does not work relationally, largely dispensing with classic table patterns. The system’s simple design is particularly impressive due to its high user-friendliness and speed. The system itself is very sleek but can be expanded in a variety of ways, which is why it is one of the most frequently used key-value stores in the world.

Intended use

MongoDB is, above all, an expert in the field of big data. If you need to manage large amounts of data and different data types, the NoSQL solution offers all the right prerequisites. The system is also designed for increasing requirements and therefore grows along with them. MongoDB has established itself in primarily for content management, for e-commerce solutions and applications that should remain freely configurable and require constant, real-time analysis.

In comparison, Redis relies predominantly on the speed factor. Like MongoDB, it also stores data in key-value pairs and supports numerous data types. The standard response times of less than one millisecond is a special feature, which enables the processing of countless simultaneous requests in real-time. This makes Redis an ideal choice for caching or session storage, where frequently used data of different types needs to be made available as quickly as possible. Other areas in which mainly Redis is used are messengers and chat rooms, (online) games, real-time analyses, streaming, financial services and the Internet of Things. Redis can be scaled both horizontally and vertically.

Functionality

Our comparison of MongoDB vs. Redis shows that their approaches and functions differ. Although both systems choose a non-relational approach, they interpret it differently. MongoDB stores data as documents in BSON format and bundles these documents into collections. This data can be structured, semi-structured or unstructured. The documents consist of key-value pairs, whereby the key is always a character string and the value can consist of other documents, arrays, Boolean values or other file types. In order to ensure high availability, MongoDB relies on sharding, in which data is distributed across several nodes. Queries are made using the MongoDB Query Language.

Redis achieves its extremely high speeds because all data is stored directly in RAM and can therefore be made available immediately. This means that the latency is quite low compared to most other solutions (despite this the storage space is limited). Like its opponent in the MongoDB vs. Redis comparison, Redis also relies on key-value pairs. The in-memory database supports different values and data structures, such as hashes, lists, sets, streams and strings. The respective keys are stored in a dictionary and a parser is used to process multiple values. There are modules for additional query functions.

Performance

MongoDB is a fast database that enables high-speed read and write queries. Thanks to the schema-free structure of the NoSQL solution, there are no delays even with large volumes of data. This speed is also achieved through a combination of the different memories. However, when comparing MongoDB vs. Redis, the in-memory database is usually significantly faster. As the data is stored directly in the main memory, it is available immediately, which is why Redis is the optimal solution if content needs to be retrieved as quickly as possible. However, this also costs RAM. At 4 GB per 100,000 assets, consumption is around four times as high as with MongoDB.

Scalability

A completely different picture emerges when comparing the scaling options in the MongoDB vs. Redis comparison. Although both systems offer generally good options, in this area it’s MongoDB that shines. The database is designed in such a way that it can grow horizontally without restrictions and manages a wide variety of data types. Sharding distributes data in a way that makes it both available and able to be processed particularly effectively. Although Redis offers horizontal and vertical scaling, it only ever uses one shard by default. Only hashed sharding is possible and management must be carried out manually.

Availability

Sharding also has a positive effect on the availability of data in a MongoDB database. The system uses replica sets and allows users to create up to 50 replicas of a file. These can then be stored on different nodes. Automatic failover functions not only determine a primary point, but also automatically replace it immediately in the event of a failure.

Redis also offers high availability and uses different nodes if required. However, there is no automatic failover unless this is set up manually by the administrator. If this is not the case, the failover must also be initiated independently.

Compatibility

When you compare MongoDB vs. Redis, the biggest similarity is probably their excellent compatibility with operating systems and programming languages. As cross-platform systems, both competitors work under Linux, macOS and Windows. MongoDB also offers Solaris and Redis has BSD in its program. The selection of possible programming languages is also huge in both cases.

Query language

The query is performed differently for MongoDB and Redis. MongoDB relies on its own MongoDB Query Language (MQL), which supports a syntax similar to JSON. This also enables data analyses and queries across multiple areas and keys. Redis, on the other hand, does not have its own query language and instead uses simple commands to simplify and speed up data searches. Only key-value queries are possible by default. For further options, you need to integrate additional modules.

Two open-source databases

Common to both MongoDB and Redis is the open-source approach that both systems pursue. Both rely on open standards that are used and further developed by a dedicated community. MongoDB provides additional commercial versions such as Enterprise or Atlas (for use in the Cloud). These offer additional security features and receive professional support.

Which companies use MongoDB and Redis?

There are numerous large companies that rely on one of the two contenders in our comparison of MongoDB vs Redis. Some of the best-known users of MongoDB are:

• Adobe
• Amadeus
• AppScale
• Craftbase
• Disney
• Etsy
• Foursquare
• Lyft
• MTV
• The New York Times
• Via Varejo

Among other companies and platforms using Redis are:

• Airbnb
• Craigslist
• GitHub
• HelloFresh
• InstaCart
• Instagram
• Pinterest
• Slack
• Snapchat
• StackOverflow
• Trello
• Uber
• X (formerly Twitter)

Is MongoDB or Redis right for you?

So who wins in the MongoDB vs. Redis comparison? The answer depends hugely on your requirements. If you need a database that is characterized by high speed and immediate data availability, Redis is your optimal choice. If your main focus is on big data and the greatest possible flexibility, you can’t go wrong with MongoDB. But if in doubt, you don’t have to choose at all! MongoDB and Redis also work extremely well together and can combine their respective strengths. This allows you to benefit from the speed that Redis offers while retaining all the scaling options of MongoDB.