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Work with Realm Files - React Native SDK

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  • Realm Files
  • Auxiliary Files
  • In-Memory Realms
  • Find a Realm File Path

Realms are the core data structure used to organize data in Realm Database. At its core, a realm is a collection of the objects that you use in your application, called Realm objects, as well as additional metadata that describe the objects.

Realm Files

Realm stores a binary encoded version of every object and type in a realm in a single .realm file. The file is located at a specific path that you define when you open the realm.

Tip

Implement Compacting in Your Production Application

Every production application should implement a shouldCompactOnLaunch callback to periodically reduce the realm file size.

Auxiliary Files

Realm creates additional files for each realm:

  • realm files, suffixed with "realm", e.g. default.realm: contain object data.

  • lock files, suffixed with "lock", e.g. default.realm.lock: keep track of which versions of data in a realm are actively in use. This prevents realm from reclaiming storage space that is still used by a client application.

  • note files, suffixed with "note", e.g. default.realm.note: enable inter-thread and inter-process notifications.

  • management files, suffixed with "management", e.g. default.realm.management: internal state management.

If you delete a realm file or any of its auxiliary files while one or more instances of the realm are open, you might corrupt the realm or disrupt sync.

You may safely delete these files when all instances of a realm are closed. Before you delete a realm file, make sure that you back up any important objects as you will lose all unsynced data in the realm.

In-Memory Realms

You can also open a realm entirely in memory, which will not create a .realm file or its associated auxiliary files. Instead the SDK stores objects in memory while the realm is open and discards them immediately when all instances are closed.

Find a Realm File Path

The realm file is located at a specific path that you can optionally define when you open the realm.

// Open a realm.
const realm = await Realm.open({
  schema: [Car],
});
// Get on-disk location of the Realm
const realmFileLocation = realm.path;
console.log(`Realm file is located at: ${realm.path}`);
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