Prerequisites

Before you can use MongoDB as a source endpoint in a Replicate task, make sure that the following prerequisites have been met:

• MongoDB must be configured with "majority" read concern level (which requires supportsSnapshotReadConcern and supportsCommittedReads to be enabled). Note that the WiredTiger storage engine (the default) is already configured with "majority" read concern.
• Before starting a task with the Full Load and/or Apply Changes replication options enabled, set the Transaction consistency timeout value in the task settings' Full Load Tuning tab to 0. This is important for preventing the capture of old transactions.
• The user specified in the endpoint settings must be granted the "read" role for databases from which you wish to replicate.
• To capture changes, the user specified in the endpoint settings must have privileges that grant changeStream and find actions on all non-system collections for all databases in the deployment (for example: "readAnyDatabase" role).
• To enable Replicate to detect changes, MongoDB databases servers must be set up in a replica set configuration. In such a configuration, change operations are recorded in the primary server's oplog, which is periodically accessed by Replicate. Note that although a Replica set usually contains multiple servers (one primary and any number of secondary servers), creating a Replica set with only a primary server - i.e. without secondary servers - is also sufficient, as the changes will still be written to the oplog.