Note: This is an updated version of an earlier Mobile Database Comparison. Last Update: 2021.

According to the database of databases there are more than 700 databases as of 2021. However, that list does include hobby projects. DB-engines “only” lists databases that have significant traction and are well-maintained; they still count more than 300 databases as of 2021. However, only a handful of these databases are edge database.

What is an edge database?

An edge database is a database that runs directly on restricted devices locally. It is a local on-device database as opposed to a cloud database. The term edge database is too young to have a Wikipedia article. However, we see it used in the IoT industry increasingly. In the field of IoT applications, it is especially important to distinguish databases that run locally on the device (“on the edge of the network”) and thus support Edge Computing from databases that run “in the cloud”. A mobile database is an edge database that runs on mobile devices, meaning the only difference between the terms edge database and mobile database is the operating system / device support they offer.

What is a mobile database?

While Wikipedia defines a mobile database as “Mobile computing devices (e.g., smartphones and PDAs) store and share data over a mobile network, or a database which is actually stored by the mobile device,” we solely refer to the latter ones as a mobile database. Meaning only databases that run on the mobile device (as the edge device) itself, locally, and store the data on the device. Therefore, we also refer to it as “on-device” database.

What are the advantages and disadvantages of working with SQLite?

SQLite is easily the most established edge database and probably the only “established” mobile database. SQLite is public domain and maintained by Richard Hipp. SQLite database has been around since the year 2000 and been embedded with iOS and Android since the beginning. SQLite is a relational database.

What are SQLite alternatives?

There are plenty of alternatives to working with SQLite directly. If you simply want to avoid writing lots of SQL and boilerplate code, you can use an object abstraction on top of SQLite. This abstraction layer is usually an ORM (object/relational mapper), e.g. greenDAO. While an ORM makes it easy to use SQLite at the beginning, there typically comes a point “where you hit SQLite”; so even when using an abstraction layer you need to understand SQLite and SQL in the longrun.

However, if you rather seek a complete replacement for SQLite, there are a few alternative databases: Couchbase Lite, Interbase, LevelDB, ObjectBox, Oracle Berkeley DB (formerly Oracle’s mobile database was “Oracle Database Lite”), Realm (now Mongo Realm), SnappyDB, SQL Anywhere, and UnQLite.

Obviously, if your also looking for alternatives that run in the cloud, there are a lot of cloud / server options out there that you can use as a replacement like e.g. Firebase. Though, with these your app will not work offline, response rates will be slower than with an on-device database and cannot be guaranteed, and last not least you will have much higher networking / cloud costs. You can find out more about the benefits of Edge Computing.

To give you an overview, we have compiled a small comparison table:

If you are interested in an indication of the diffusion rate of databases and mobile databases, check out the following database popularity ranking: http://db-engines.com/en/ran.

Thanks for reading and sharing. Please let us know what you’re missing.