Realm Database

Realm database or Realm DB is primarily used as a mobile database which functions as an object database. It makes storage of data for mobile and web apps easy. Realm acts as the CenterPoint of data storage and management. Experts contend that Realm is a superior alternative to other mobile database solutions like Core Data and SQLite.

Realm can function as the database solution for an extensive set of programming languages which includes:



Objective C




Developers can use common utilities like SPM or Swift Package Manager, Carthage or CocoaPods to add the Realm database solution to their development project. SPM especially is noted for being a quick and easy way to start using Realm for development.

Top Use Cases

Developers usually employ a combination of SQLite with the Room interface or the Realm DB for their apps. Let us now look at how the two database solutions fare on several key database features for mobile and web development.


Realm occupies more storage hogging than Room because it is a separate database and library. In fact, using Realm will bloat your mobile apk by a significant three to four megabytes. On the other hand, Room is a simple SQLite top layer. Usually, SQLite itself is built into the Android OS and using the tool will only increase the size of the apk by merely a dozen of kilobytes. However, along with that advantage comes at the cost of a significantly a smaller number of available methods.


When you use Realm, you can’t transfer objects across streams. In Realm, data objects exist as database values that can only be modified through the modification of the database itself. Such objects remain connected in a particular stream where the Realm instance is present and the stream from which the objects were received. Should you close a particular Realm instance in a stream, you make the extracted objects invalid. Typically, this isn’t such a big issue, but you need to exercise caution and avoid switching streams. If you do indeed decide to switch streams you need to also create new instances of the Realm database. Subsequently, you will need to re-execute queries to extract the necessary data objects.


The Room tools stores the SQLite based associated data by creating a file in an app’s inner data catalog. This ensures that no application or user can access the data unless they perform OS rooting. This works nicely for most common uses and developers who wish to strengthen app security further can use tools like SQL Cipher. It encrypts your database and thereby serves as an additional security layer. Room works seamlessly with the SQL Cipher tool, in fact the latter itself is an SQLite extension enabling strong 256-bit SQLite database encryption. Additionally, the SQL Cipher namespace can work to facilitate migration by you can use it instead of the standard SQLite API interface.

In terms of security, Realm DB boats of industry leading AES-256 encryption while at the same time maintaining high levels of transparency in its data decoding method. The initial 256 bit of the 512-bit encryption key is used for encryption and data decoding purposes while the remaining 256 bits find use as means to ensure integrity with the Hash-based Message Authentication Code or HMAC in short.


There are some extensive test results on CRUD operations execution speeds. Such tests track the relevant speeds of not only Realm and Room but also SQLite itself. As per the findings of such tests Realm is significantly swifter than its Room and SQLite counterparts.


Realm is specially intended to solve common database problems like:

  • Local storage options
  • Network reliability
  • Ensuring UIs remain reactive

Realm Features

There are some extensive test results on CRUD operations execution speeds. Such tests track the relevant speeds of not only Realm and Room but also SQLite itself. As per the findings of such tests Realm is significantly swifter than its Room and SQLite counterparts.

Local storage

Realm operates inside client devices themselves. With Realm it becomes easy to store, access and update data. Further, Realm is simple and lightweight when you compare it with other database solution options that can access objects through native queries across platforms.

Reactive UI

Realm lets objects reflect updated and live data. When using Realm, it is possible to subscribe to data modifications, thereby keeping the UI elements updated. Through the Realm SDK developers can even connect with local realms irrespective of the development language being used. It offers this feature on almost all major development platforms including:

  • iOS
  • Android
  • React Native
  • js
  • UWP
Object-based orientation

Realm can organize data in the form of objects and not as rows, columns and documents


Realm database for android is particularly suited for mobile devices due to its low-power requirements and real-time operation environment.

Network reliability

Realm works through an offline-first operation mechanism. That means that the read and written data resides locally and not over a network. You can choose to synchronize data with MongoDB Realm by enabling the Realm sync option. This enables Realm to work over networks while operating as a background thread. The protocol used here is noted for its consistent ability to resolve conflicts on all clients as well the MongoDB Atlas clusters that are linked to it.


With Realm, developers can run native queries on almost all platforms or use raw query languages that boast of universal platform compatibility.


Realm is characterized by its support of on-device encryption features and options

Cross platform functionality

As mentioned before, Realm lets developers use the same database across the following platforms:

  • Android
  • iOS
  • macOS
  • Linux
  • Windows

All you need for cross-platform interoperability is define SDK specific schemas.

Our Realm Database Expertise

iSummation has extensive experience in the development of web and mobile apps using the Realm database technology. Our pool of Realm experts makes effective use of the database to build apps that perform and function better.

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