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Realm (database)

From Wikipedia, the free encyclopedia
Original author(s)Alexander Stigsen and Bjarne Christiansen
Developer(s)MongoDB Inc.
Initial releaseJanuary 2017; 7 years ago (2017-01)
Written inC++
TypeObject database
LicenseApache License 2.0

Realm is an open source object database management system, initially for mobile operating systems (Android/iOS)[1] but also available for platforms such as Xamarin,[2] React Native,[3] and others,[4][5] including desktop applications (Windows[6]). It is licensed under the Apache License.

In September 2016, the Realm Mobile Platform was announced, followed by the first stable release in January 2017. It allows two-way synchronization between the Realm Object Server[7][8] and the client-side databases that belong to the given logged-in user. Both a developer and a commercial edition[9] was released, along with a business license[10] for integrating with other database management systems such as PostgreSQL.[11][12]

In spring 2019, MongoDB acquired Realm for 39 million USD.[13]



Realm's development began in the end of 2010 by Alexander Stigsen, along with Bjarne Christiansen,[14] under the name TightDB. The company started in 2011 at Y Combinator.[15] It was promoted as NoSQL with configurable durability, and the ability to share the same groups of data across multiple processes, but also even multiple devices and clusters.

TightDB renamed its product to Realm in September 2014, and released it for public testing. In March 2015, funding of about $20 million was disclosed.[15][16]

Realm was mentioned in some trade press,[17][18] including by other firms such as IBM.[19]

Realm announced version 1.0 in June 2016, and released a platform for real-time two-way synchronization (beta in 2016 September, release in 2017 January),[20] and provided a Node.js SDK for server-side applications.[21]

In May 2017, UWP support was announced.



The most notable features of Realm are the following:

  • As Realm is an object store, its typed language-specific APIs map typed objects directly into the Realm file – therefore classes are used as the schema definition.
  • Relationships between objects are allowed via "links". Each "link" creates a "backlink" as an inverse relationship to whichever objects are linking to the current object.
  • The query results returned by Realm are thread-local views to the current "database version" (as Realm handles concurrency with MVCC architecture), and these views "automatically update" when a transaction is committed from any thread, as long as Realm is able to update its instance version (which is possible on threads that are able to receive change notifications). When this happens, Realm calls change listeners that are added to its query results (if they've changed).
  • Each thread-local view returns proxy objects that only read from/write to the database when an accessor method is called, meaning all database access is lazy-loaded. Writes are allowed only while in a write transaction.
  • As each query result and each proxy object is a view to the underlying data, any change made to the database is reflected in all objects that point to the same data. Realm generally calls this behavior "zero-copy architecture" (along with the previously mentioned lazy-loaded data access).

Programming language support



  1. ^ "Realm: Object Centric Present Day Database for Mobile Applications". Retrieved 2017-04-22.
  2. ^ "Realm mobile database platform now has support for Microsoft's Xamarin". Gooroo. Retrieved 2017-04-22.
  3. ^ "Realm: Introducing Realm React Native". Retrieved 2017-04-22.
  4. ^ "Realm: Microsoft Xamarin 1.0, Azure, Windows Desktop". Retrieved 2017-04-22.
  5. ^ "Realm Mobile Platform Supports Xamarin, Microsoft Azure – ADTmag". ADTmag. Retrieved 2017-04-22.
  6. ^ "Using Realm Mobile Database in a converted desktop app with the Desktop Bridge". App Consult Team. Retrieved 2017-04-22.
  7. ^ Kepes, Ben. "Realm broadens its mobile database offering with Object Server". Network World. Retrieved 2017-04-22.
  8. ^ "Realm broadens its mobile database offering with Object Server | The Diversity Blog – SaaS, Cloud & Business Strategy". www.diversity.net.nz. Retrieved 2017-04-22.
  9. ^ "Realm launches commercial edition of its mobile database – SiliconANGLE". SiliconANGLE. 2017-01-19. Retrieved 2017-04-22.
  10. ^ "Realm Open Sources Mobile Database, Grows It into Enterprise Platform – ADTmag". ADTmag. Retrieved 2017-04-22.
  11. ^ "Realm Makes PostgreSQL Real-Time with New Connector". Database Trends and Applications. 2017-03-21. Retrieved 2017-04-22.
  12. ^ "Realm's Mobile Development Platform Links to PostgreSQL to Tie into Enterprise Data – The New Stack". The New Stack. 2017-03-21. Retrieved 2017-04-22.
  13. ^ Miller, Ron. "MongoDB to acquire open-source mobile database Realm for $39 million". techcrunch.com. Retrieved 2019-04-25.
  14. ^ "A startup launched 9 months ago by these former Nokia engineers is going absolutely bonkers". Business Insider. Retrieved 2017-04-22.
  15. ^ a b Ron Miller (March 24, 2015). "Realm Can Expand Its Reach With $20M Investment". Tech Crunch. Retrieved May 21, 2017.
  16. ^ "Form D: Notice of Exempt Offering of Securities". March 30, 2015. Retrieved May 21, 2017.
  17. ^ Krill, Paul. "Realm revives object database for mobile dev". InfoWorld. Retrieved 2017-04-22.
  18. ^ Thomas Claburn (September 29, 2016). "Realm – a database you may not have heard of but app devs have – touts cloudy platform". The Register. Retrieved May 21, 2017.
  19. ^ "Visual Recognition Mobile App with Watson, Realm, and Swift – IBM OpenTech". IBM OpenTech. 2016-12-12. Retrieved 2017-04-22.
  20. ^ "Realm: Introducing the Realm Mobile Platform". Retrieved 2017-04-22.
  21. ^ "Realm Releases Object Database for Node.js". InfoQ. Retrieved 2017-04-22.