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Device Sync Logs

On this page

  • Overview
  • Connections
  • Sessions
  • MongoDB Atlas Sync Events
  • Fields

Atlas Device Sync creates sync logs whenever a user interacts with Sync. This includes writing data to Atlas App Services from clients, reading changes from App Services to clients, and starting or ending a connection.

Every user communicates with App Services using a connection. Each connection uses a single websocket to push and pull information to and from a single user. Logging in a user using any authentication provider starts a connection. Logging out that user ends the connection.

Users download and upload changes to a synced realm using a session. Instantiating a local instance of a synced realm starts a session. Destroying that realm object ends the session.

Every sync event is associated with a user identity that tells you exactly which user caused the event to occur. However, you may notice some sync events that aren't associated with any specific user. These events include downloaded changes from all clients as well as as well as any change made in MongoDB Atlas. Any sync event that does not include a user ID is part of the MongoDB Atlas data synchronization process. You may see a large number of MongoDB Atlas synchronization events when you initialize sync if your cluster already contains a large amount of data.

Debugging information about the operation. Includes the schema version on client and server, the number of changes, and whether or not conflict resolution was required in order to incorporate the operation into the server's copy of the data.
Write Summary

Includes information about the data that changed, such as:

  • The type or table of data that changed.

  • The operation used to change data: insertion, deletion, update, or replace.

  • The primary key of the data that changed.


The SDK used to send the request. Potential values include any SDK. For a browser, this is <browser> <SDK version>.


This request came from the Realm Web SDK version 4.0.0 running on Mozilla Firefox:

SDK: firefox v4.0.0

This request came from the Realm Java SDK version 4.6.0 running on Android Marshmallow:

SDK: android v4.6.0
Platform Version
The version of the platform that sent the request.
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