Home MongoDB Redis vs. MongoDB: What you need to know

Redis vs. MongoDB: What you need to know

by Abraham
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redis vs. mongodb

Databases are garnering a lot of popularity every day and are used by many organizations for a wide variety of use cases. Many organizations are employing innovative techniques to handle their data storage. These companies often shift between databases to optimize their storage and data mapping according to their business needs.

Companies with growing data requirements utilize databases with dynamic functionalities. However, deciding which database is perfect for each of these companies can be very subjective. When it comes to database management, choosing between Redis and MongoDB can be relatively challenging.

This article will provide a comprehensive analysis of both databases and give the differences. In addition, the article will also provide you with a brief overview of both Databases along with their features.

Introduction to Redis

Remote Dictionary Server (Redis) is an open-source data platform that supports the storage of various data types and vast volumes of data with a functional velocity. It provides data structures such as strings and lists with range queries, bitmaps, hyper logs, geospatial indexes, and streams. It contains in-built replication, Lua scripting, LRU eviction, transactions, and different levels of on-disk persistence. It provides high availability via Redis Sentinel and automatic partitioning with the Redis cluster.

Traditional Databases come with drawbacks that Redis solves. These drawbacks include; lack of support for different data types and insufficient memory for storing large amounts of data. The weaknesses in RDBMS are solved using NoSQL Databases such as Redis.

Redis works with an in-memory dataset to achieve its highest performance. A user can persist their data by dumping the dataset to disk periodically or by appending each command to a disk-based log depending on their use case. They can also disable persistence if they need a feature-rich, networked, in-memory cache.

Redis supports asynchronous replication with quick non-blocking first synchronization and auto reconnection with partial resynchronization on netsplit. Redis also includes other features that most programming languages can use. Since Redis is written in ANSI C, it works in most Posix systems such as Linux and OS X without needing external dependencies. These two operating systems are where Redis is developed and tested mostly. It is recommended to use Linux for deployment. Redis may also work in systems derived from Solaris, such as SmartOS. Redis does not have official support for Windows builds.

Why is Redis different from other database systems?

The idea of a system that is considered a store and a cache simultaneously was made famous by Redis. It utilized a design where data is constantly modified and read from the central computer and stored on disks unsuitable for random data access. Furthermore, this design reconstructed the data back in memory once the system restarts. At the same time, Redis provides a data model that is unusual compared to a Relational database Management System (RDMS).

In Redis, user commands perform specific operations on given abstract data types rather than describing a query executed by the database engine. Therefore, data must be stored suitably for quick retrieval without help from the database system in the form of secondary indexes, aggregations, or other features standard in traditional RDBMS.

Implementation of Redis makes use of the fork system call to duplicate the process that holds the data so that the parent process continues to serve clients while a copy of the data is created on the disk by the child process.

Redis data types

Redis differentiates from other structured storage systems by not only supporting strings but also abstract data types such as; Lists of strings, sets of strings (which are collections of non-repeating unsorted elements), hash tables in which keys and values are strings, sorted sets of strings (which are collections of non-repeating elements ordered by a floating-point number called the score), stream of entries which include consumer groups and Geospatial data.

Other data types that are supported based on Redis Modules API include;

  1. Graph- RedisGraph, which implement a queryable property graph
  2. Bloom filter – RedisBloom which implements a set of probabilistic data structures for Redis
  3. Time series – RedisTimeSeries which implements a time series data structure
  4. JSON – RedisJSON, which implements the JavaScript Object Notation data Interchange Standard (ECMA-404) as a native data type

Redis popularity

According to the monthly DB-Engines rankings, Redis is usually the most popular key-value database. It has also been ranked the fourth NoSQL database in user satisfaction and market presence based on user reviews. It is also the most popular NoSQL database in containers and ranked fourth in Datastore of 2019 by ranking website stackshare.io. The Stack Overflow developer survey of 2017,18,19,20 and 21 was voted the most loved database.

Key features present in Redis

A wide range of features is present in Redis hence making it a popular choice over other databases. These features include:

  1. Tenacity- This database allows storing several data types in the main memory. Asynchronous data changes as per updates are saved on the disk based on the elapsed time or when the data was updated. It also provides high availability and an append-only file persistence mode.
  2. Speed- This database is swift compared to other data stores. Redis claims it is faster because it stores large volumes of data in the primary memory within a fraction of a second.
  3. Lua scripting- This scripting works as one of the fastest executing scripts. Redis built its script in the Lua language to achieve its aim to serve users with speedy data services. Lua is beneficial since its initialization is faster, executing scripts faster without disturbing or slowing down the database for a response.

Introduction to MongoDB

MongoDB is an open-source NoSQL database that accepts values in BSON format. It does not take input values in table format. data is stored in collections and documents since MongoDB is a document-oriented database. This database overcomes some drawbacks that were present in traditional RDMS.

Many developers always struggle with tasks such as replication, the partition of data, and the time-consuming writing process. MongoDB is a perfect database solution that overcomes these problems and is lightweight, flexible, and precise.

Key features present in MongoDB

This database includes innovative features that make it a popular choice among other databases. These features include:

  1. Scalability- This database supports horizontal scaling of data using the help of Sharding which is partitioning data over several servers. Large volumes of data are divided evenly across several data chunks managed by a master node. This makes inserting new machines over existing running databases a possibility.
  2. Data replication and higher availability- data loss or restarting the entire setup to store data again is the main concern whenever a hardware failure is experienced. MongoDB is loaded with data replication features which stores copies of data on various data servers. The data can be retrieved anytime, depending on the user’s requirement. Hardware failure within a user’s setup is also prevented using this feature.
  3. High performance- You can experience increased performance on all MongoDB operations. This is because this database avoids redundant input/output operations, as is common in other relational databases. The indexing process in MongoDB is a lot faster hence making select queries deliver faster results.

MongoDB editions

Several MongoDB editions have been released. These editions include:

  • MongoDB Community Server- This MongoDB edition is free and is available for Windows, Linux, and macOS
  • MongoDB Enterprise Server- This is the commercial edition of MongoDB and is available as part of the MongoDB Enterprise Advanced subscription
  • MongoDB Atlas- This is an on-demand, fully managed service and runs on AWS, Microsoft Azure, and Google Cloud platforms.

Differences between Redis and MongoDB

1. Performance

Large volumes of workload are handled more comfortably in Redis compared to MongoDB. Redis runs on a single core; hence it is single-threaded. Therefore, in terms of performance, Redis is slightly better than MongoDB. MongoDB is also prone to responding slowly once bound by the CPU.

2. Features

MongoDB is loaded with features such as data aggregation and map-reduce. On the other hand, Redis has persistence, caching, and hassle-free crash solutions. In Mongo DB, you can provide a role-based accounting control which is not possible in Redis.

3. Scalability

The scalability factor is supported better in MongoDB than Redis because RAM functionality on physical systems is optimized with MongoDB, whereas in Redis, RAM use is limited. Although peripheral features in Redis are extensive, scaling is more comfortable in MongoDB.

4. Platform Support

Redis is an in-memory data structure platform allowing caching and supporting message brokers. At the same time, MongoDB is a cross-platform NoSQL database that offers spring data support, an interactive command-line interface for querying and supporting BI connectors for analytics. Redis, with the help of java clients, offer spring cache support.

5. Database Architecture

MongoDB is a document-oriented database. Its database architecture contains a distributed systems design, a document data model, binary import and export tools, data import and export tools, diagnostic and security tools, and MongoDB compass. Redis’ database architecture contains Redis client and Redis server, storing data in memory.

6. Programming Language

Redis supports these programming languages; Crystal, Clojure, Dart, Elixir, Fancy, C, C#, Haxe, Lisp, Lua, JavaScript, Pascal, Pure data, MatLab, Objective-C, Python, rebol, ruby, scheme, swift, Visual basic, and Tcl.
MongoDB also supports multiple programming languages such as C++, C, Rust, Scala, Swift, Smalltalk, PHP, Powershell, Prolog, Python, R, Perl, Dart, Erlang, Groovy, and Haskell.

7. Replication support

MongoDB supports Master-slave replication, while Redis supports master-master replication and master-slave replication.

8. Pricing

Redis’ Enterprise cloud varies as per the data storage requirements. Its license follows a subscription-based model. The basic pricing plan for Redis is free, although, for advanced versions, $7 per month is the beginning price.
Mongo DB’s basic plan is also free, but additional commercial license pricing starts at $57 per month.

9. Security

MongoDB is strict about security by providing authentication protocols and encrypted data that validate a user. It also allows access and authority specification in which users assign role-based account control hence improving security.
Although Redis has strict authentication protocols followed before executing commands, it provides users with a simple password-based authentication that may put security at risk.

Challenges that users encounter with Redis

There are several problems that a user can encounter while working with Redis. These problems include;

  1. Latency troubleshooting issues- This occurs because of extreme delay on the client’s end while communicating. Also, the processing capacity of Redis is lower hence leading to probable delays.
  2. Crashes- These may occur while debugging an event. It can be resolved by providing your debugging details to the developer community. It also might occur due to the release of new versions of the Redis product.
  3. System crashes during updates- This problem might load your server’s RAM, which might leave your system hanging for a while. To resolve this, you can test your RAM over Redis-server-test-memory.

Challenges that users encounter with MongoDB

While working with MongoDB, a user may encounter problems such as an occasional server failure. Other problems include:

  1. MongoDB follows complex procedures such as manual configurations and moving parts for scaling to a fully shared environment from a single replica. This problem is encountered due to MongoDB’s master-slave architecture.
  2. Performance reduces as the number of users increases due to single node availability. Expanding the setup can rectify this situation.
  3. MongoDB may cause data loss and inconsistency. Even though it has layered data replication features, it sometimes lacks handling a complex replication process.


This article has provided a comprehensive analysis of the popular databases in the market today, Redis and MongoDB. It has discussed both databases and their features and limitations. We hope that this article has helped you understand these two databases, and you may be able to choose which is better suits you and your project based on the features that each provides. In case of any problem, reach us through the comment section, and we will get right back to you.

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