Connection requirements
- A standard connection string (mongodb:// or mongodb+srv://) for a replica set — Atlas clusters qualify automatically
- A standalone (non-replica-set) MongoDB cannot run CDC — change streams require an oplog, which only exists on a replica set
- A user with the built-in read role on every database you intend to migrate
- If using Atlas, the worker's outbound IP (or 0.0.0.0/0 for evaluation) added to Network Access
Oplog-based change streams
CDC opens a MongoDB change stream, which is backed by the oplog. Every insert, update, and delete is delivered in order with a resumable token, so a restart resumes from the last applied event instead of re-scanning the collection.
Setup
1
Add the connection
Paste the connection string under Connections → Add. NoSQLSync verifies it can list databases before saving.
2
Introspect
Pick a database and collection. NoSQLSync samples documents to infer field types, including nested objects and arrays.
3
Enable CDC
Choose mode "cdc" on the migration. The oplog tail starts after the initial bulk load completes.
FAQ
Does this work with a standalone MongoDB (no replica set)?
Bulk (one-time) migration works against a standalone server. CDC does not — MongoDB only exposes change streams on a replica set or sharded cluster, so a standalone source fails fast with a clear error instead of hanging.
What permissions does the connection user need?
The built-in read role on each database being migrated is sufficient. No admin or cluster-level role is required.