Mobile OS is growing bigger and widely spread in a few years. As this OS is growing larger and hardware as powerful as any normal computing device, data computation from mobiles is also increasing. A database is the most common way of storing and managing data. Databases are handled on server-side or cloud and mobile devices only communicate with them through the network. However, to make applications more responsive and less dependent on network connectivity, the trend of offline usage or less dependency on the network is gaining popularity.
Nowadays, applications keep database locally or make a copy of database over cloud onto local device and sync with it once in a day or whenever there is network connectivity. This will help in faster and responsive applications which are functional even when there is no or limited internet connectivity.
There are lots of mobile databases coming into the market but not all of them satisfy all requirements. So, here we discuss the most popular databases for Android apps.
Let's get started -
Firebase is built on Google infrastructure and scales automatically, for even the largest apps. It gives you functionality like analytics, databases, messaging and crash reporting so you can move quickly and focus on your users. Firebase products work great individually but share data and insights, so they work even better together.
The realm is a relational database management system which is like conventional databases, data can be queried and filtered, interconnected, and persisted but also have objects which are life and fully reactive. Realm DB is developed by Realm and specially designed to run on mobile devices. Like SQLite, Realm is also serverless and cross-platform. It can be stored both on disk as well as in memory.
Couchbase Lite is a powerful NoSQL embedded JSON database. It is a highly scalable DB with enterprise-level security. Data in Couchbase Lite is stored as JSON documents. Each document can have one or more attachments which are stored and loaded separately from documents. Couchbase is an offline first DB and sync with Cloud is needed or when a network is available. Couchbase Lite runs locally on the device and persists data as JSON and binary format. All crud operations performed on local DB. A developer does not need to write sync code (if needed) to sync local DB with a cloud, it is handled by Sync Gateway. Couchbase Lite comes with a conflict resolution mechanism that is quite similar to the one used by Git.
SQLite is relational DB, a lighter version of SQL designed for mobile. It is an in-process library that implements a self-contained, serverless, zero-configuration, transactional SQL database engine. SQLite supports all the relational databases features and is open source compact library which is by default present in two main Mobile OS i.e. Android and iOS, and supported by blackberry and Windows phone. It is an embedded SQL Database engine without any separate server process, unlike any other SQL database. It is very fast and needs very less memory to operate.
ORMLite is a lighter version of Object Relational Mapping which provides some simple functionality for persisting Java objects to SQL databases. It's ORM wrapper over any mobile SQL related DB. ORMLite is used to simplify complicated SQL operations by providing a flexible query builder. It also provides powerful abstract Database Access Object (DAO) classes. All in all, ORMLite is a good SQLite replacement if an application is big and complex in terms of DB usage.
UnQLite is an open-source database that exposes both a key-value and a document store interface. It supports both in-memory and on-disk databases, transactions, multiple concurrent readers, and cursors for linear traversal. Like SQLite, UnQLite uses a cross-platform file format, and stores each database in a single file on disk. UnQLite storage engine works with key-value pairs. A distinctive feature of UnQLite is that you can change at run-time the storage engine that is used.
Berkeley DB can handle data in many ways. It can be in a relational way like SQLite, or it can be in Key/Value pair data as byte arrays and supports multiple data items for a single key. It is an open source high performance embedded DB. It also supports Java objects as data or it can also be XML documents. Different libraries provide different types of API to handle multiple formats but all packaged Berkeley DB.
LevelDB is an open-source library written at Google that implements a key-value store, where keys and values are byte arrays, and data is stored ordered by key based on some, probably custom, comparison function. LevelDB supports atomic batch updates, forward and backward iteration over the contents of the store, snapshots, caching, data integrity, and automatic data compression. An important limitation imposed by the library is that at any moment at most one process can have access to a specific database.
Let us know which DB is best for your Android app development. You can also suggest some other DBs which not mentioned above if those are best. You can also share your experiences with us in the comment section. Thank you!