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    Realm vs SQLite – Which is the better local database?

    • January 03, 2024
    • 6 min

    Before starting any app development project, the tech stack is decided. Furthermore, choosing the right tech stack is crucial for the success of the project. Thus, when choosing a local database for their app, many businesses get confused and it’s difficult for them to pick one from the several available databases. In this post, we will look into the detailed comparison between Realm and SQLite and discuss which one would be perfect for you.

    Realm vs SQLite – An Introduction

    • SQLite: A C-based local database called SQLite enables programs to use a SQL interface to store and retrieve data from local files on devices. In September 2000, SQLite was launched as an open-source project. It is compatible with a limited number of platforms, mostly desktop and mobile operating systems. But just a small number of individuals maintain it, and the developers have strict control over what is created.
    • Realm: On the other hand, Realm database offers a quick, scalable replacement for SQLite that simplifies data syncing, querying, and saving. Developers may work directly with native objects thanks to the object-oriented data model; ORMs and DAOs are not needed. Additionally, developers can effortlessly backup, handle, and evaluate app data in the cloud by utilizing the full potential of MongoDB Atlas thanks to built-in edge-to-cloud data sync. The Realm SDKs are accessible for the majority of widely used platforms, languages, and frameworks and are free of cost.

    In short, SQLite follows a traditional relational database model and requires writing SQL queries and Realm uses object-based data models, which makes it easier for developers to work with and reduces the amount of boilerplate code.

    Realm vs SQLite – Data Modeling

    • Realm: Realm handles relationships between objects in an intuitive manner. Developers can establish relationships between objects using properties, and these relationships are easily navigable. There is no need for complex JOIN operations typically associated with relational databases like SQLite. Furthermore, Realm supports dynamic schema, enabling changes to the data model without the need for migrations. This flexibility can be advantageous during the development and iteration phases.
    • SQLite: Developers interact with the database using SQL. Relationships between tables are established using foreign keys, and JOIN operations are often necessary for querying related data. SQLite databases require a structured schema that defines the tables, their relationships, and the data types of each column. Changes to the schema may require migrations, especially in production environments. SQLite encourages the use of normalization principles to minimize data redundancy and maintain consistency. This involves breaking down data into separate tables to reduce duplication.

    Realm vs SQLite – Performance

    • Realm: Realm provides a simpler and more intuitive API compared to SQLite. It is known for its fast performance due to its use of a C++ core and direct mapping to objects. It can outperform SQLite in certain scenarios, especially for read-heavy operations. Furthermore, this local database employs lazy loading, loading only the data that is explicitly accessed. This can lead to improved query performance as unnecessary data is not loaded into memory. Additionally, Realm excels in scenarios requiring real-time data updates. It efficiently tracks changes and automatically updates the UI in response to database modifications.
    • SQLite: SQLite is generally fast and efficient for most use cases. It may have better performance for write-heavy operations or complex queries but not better than Realm. Thus, carefully crafted queries and indexes are crucial for optimizing performance. SQLite databases are typically compact and self-contained. This can be advantageous for applications with limited storage resources, contributing to quicker data access times.

    Realm vs SQLite – Offline Capabilities

    • Realm: This local database is designed with built-in offline support, making it well-suited for applications that require seamless offline functionality. Data can be read and modified locally even when the device is not connected to the network. Realm includes conflict resolution mechanisms to handle situations where conflicting changes are made both locally and on the server during an offline period. Furthermore, Realm provides automatic synchronization, meaning that changes made offline are synchronized with the server when a network connection is re-established. This real-time synchronization ensures that the local and remote data stay up-to-date, contributing to a consistent user experience.
    • SQLite: SQLite primarily operates in an offline mode by default. Applications using SQLite store data locally on the device without requiring a continuous network connection. Developers need to implement custom synchronization logic if real-time synchronization with a remote server is necessary. Unlike Realm’s automatic synchronization, SQLite requires developers to implement their own synchronization mechanisms when a network connection becomes available. This manual approach provides flexibility but requires additional development effort.


    In many ways, Realm local Database is better than SQLite with Core Data and/or Room as a contemporary. Building cross-platform, offline-first apps is made possible by the full power of the MongoDB Realm and MongoDB Atlas cloud platforms. Consideration of factors such as ease of use, performance, offline capabilities, data modeling preferences, and the specific needs of your application are essential in making an informed decision. Real-world testing and alignment with your project’s goals will help determine which database solution is the better fit for your development needs.


    Is Realm or SQLite better for mobile app development?
    Both Realm and SQLite are widely used in mobile app development. Realm is known for its ease of use, real-time synchronization, and object-oriented model, making it a popular choice for certain scenarios. SQLite, with its traditional relational database model, is favored in applications with complex data structures and those requiring extensive SQL querying capabilities.
    Does Realm support automatic synchronization in offline mode?
    Yes, Realm provides built-in offline support and automatic synchronization, allowing seamless data read and modification even when the device is offline. Changes made locally are automatically synchronized with the server when a network connection is reestablished.
    Which database is more performant, Realm, or SQLite?
    Performance depends on the specific use case. Realm is often praised for its fast read and write operations, especially in scenarios with real-time updates. SQLite, while generally fast and efficient, may be preferred in applications with complex querying requirements or a need for transactional integrity.
    Do I need to use an ORM with SQLite?
    Using an Object-Relational Mapping (ORM) library is a common practice when working with SQLite, as it simplifies the mapping between the relational database and object-oriented programming languages. Realm, however, integrates directly with native objects, eliminating the need for additional ORM layers.
    Is Realm suitable for applications with complex data relationships?
    Yes, Realm is well-suited for applications with complex data relationships. Its object-oriented model allows for easy representation of relationships between objects without the need for complex JOIN operations.

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