ROOM VS MongoDB Realm Database in Android


Most of the apps you use on daily basis store data on mobile devices. It could be anything like storing messages, contacts, images, music, and other files. Anything that is available for you without access to the internet is obviously stored on a device. For this, we use a database to store this persistent data.

Data persistence is a very important part of Android Development. it ensures that the data isn't lost or removed even when the app is closed, the data downloaded from the internet is safely saved on the device, so it doesn't need to reload the data and is user ready.

There are two main categories of databases SQL databases (Relational) and NoSQL databases. 

Mostly used SQL databases are SQLite, LiteDB, Coredata, Oracle Database Lite, extremeData, and many more in the line. Whereas in the case of NoSQL Mongo Realm/ Realm DB, Couchbase, UnQLite, etc. Nowadays, Room and Realm db is very popular and used amongst developers, so we are going to compare Room which is an abstraction layer on top of an SQLite Database, and Realm Database, which is a NoSQL database, in detail.

Room Database

Previously most of the apps use SQLite database, which is a standard library to store data using a specialized language (SQL) to perform database operations. Now we use Room which is a persistence library that's part of Android Jetpack. Room is an abstraction layer on top of an SQLite database. Instead of using SQLite directly, Room simplifies the chores of database setup, configuration, and interactions with the app. The room also provides compile-time checks of SQLite statements.

Room database is an open-source database library created by Google exclusively for Android applications. It is intended to be a compact, effective, and user-friendly replacement for conventional SQLite databases. So what are the main factors that make a room database a good choice for us? Room Libary uses the idea of an object-relational mapping orm to map Java or object-oriented objects to a database table. With room, we basically define entities that represent the tables in the database and also a Dao interface where we specify all kinds of interactions that we want to have with those tables as well as write some custom SQL queries.

Benefits and drawbacks of Room:

Simple: To define and query the database schema, Room offers a clean and concise API. With little boilerplate code, developers may construct entities, relationships, and data access objects (DAOs).

Compile-time Checks: SQL queries are subjected to compile-time tests by ROOM, which helps identify issues early in the development process. This lowers the likelihood of SQL runtime problems.

Integration with LiveData and ViewModel: ROOM enables reactive data updates and increased UI responsiveness by smoothly integrating with Android Architecture Components like LiveData and ViewModel.

Mature and Stable: As a component of the official Android toolkit, Google maintains, supports, and documents ROOM.

Security: On the other hand, this library has some security flaws. For example, when it comes to security, a room does not offer user-based management, and you will need to take care of database security on your own. Additionally, there is no native built-in encryption, so users must use third-party encryption libraries.

Cross-Platform Support: The second drawback is a lack of cross-platform support, so if you want to create cross-platform applications or other diverse web interfaces, you will need to base your projects on several frameworks and the principles that each one offers. In other words, MongoDB Realm.

Realm Database

Realm is a cloud-based database built on top of the well-known document-oriented database MongoDB. It has a built-in Edge to cloud data synchronization service that enables developers to easily backup, manage, and analyze mobile application data in the cloud using the full power of a MongoDB atlas. The MongoDB Atlas is a cloud-based platform that is designed for use across multiple platforms, including web and mobile applications.

Benefits and drawbacks of Realm:

NoSQL Flexibility: Flexible NoSQL data structures are possible thanks to MongoDB Realm's NoSQL-based database. This can be helpful for applications where a relational database could be too rigid or where data formats might change often.

Real-time Synchronisation: Real-time synchronization is one of Realm's unique features. Real-time updates are made possible by the automatic propagation of changes performed on one device to other devices and the cloud.

Security: When using a MongoDB atlas for data synchronization, the realm database offers native encryption. Additionally, there are built-in authentication and authorization rules that make it simple to manage which users can read data.

Serverless Architecture: Realm's serverless architecture eliminates the need for developers to handle server infrastructure, making it a practical option for teams with little experience with backends.

Cross-Platform Support: In contrast to room database and Mongodb, the realm can be used with online, mobile, and desktop apps. It also provides a variety of SDKs for various programming languages.

Learning curve: For developers that are new to this database, the MongoDB realm can be difficult to set up and operate due to its higher learning curve. 

Expensive: If you intend to retain a significant quantity of data inside the Mongodb on the cloud, that will undoubtedly cost you some money. The MongoDB realm can be costly if you intend to utilize the MongoDB atlas to synchronize the data between the server and the client.

Choosing the Right Solution

The choice between the room and the Mongodb realm will depend on the specific needs of the project. For example, if developers are building an Android application and need a lightweight and simple database, the room may be the best option. However, if developers need a database that can be used across multiple platforms, the Mongodb realm may be the best option. Here are a few situations to think about:

The room might be a better option.

  • If your app's data model closely approaches a conventional relational structure.
  • You're trying to find a local database that has great LiveData and ViewModel integration capabilities.
  • SQL query verification at compile time is essential for your development process.

MongoDB Realm might be a better option.

  • If your app needs real-time data synchronization between devices and the cloud.
  • You favor a flexible data modeling NoSQL approach.
  • The consumers of your app depend on offline support.
  • To speed up development, you wish to use a serverless backend.


Choosing the best data storage option is essential for Android app development if you want to provide a reliable and user-friendly experience. MongoDB Realm and ROOM both have unique benefits that may be tailored to different project requirements. While MongoDB Realm stands out for its real-time synchronization, offline support, and NoSQL flexibility, ROOM's relational database features offer a strong basis for local data management. You can find the option that most closely reflects your objectives by carefully analyzing the needs of your app and the level of experience of your development team.

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