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Use MongoDB as a source or destination. CDC uses Change Streams.

Connection settings

Paste the URI into the connection form to autofill. Special characters in the password (;, %, ^, +, *, :, etc.) are parsed as-is. Only encode @, /, ?, or # inside the password (%40, %2F, %3F, %23) — those delimit the URI. For MongoDB Atlas, use the connection string from DatabaseConnectConnect your application. For Railway, the MONGO_PUBLIC_URL variable does not include a database name. Enter the database name manually in the Database field — Railway will create it automatically on first use if it doesn’t already exist.

Permissions

For CDC, the user also needs access to the local database and change stream privilege.

CDC via Change Streams

MongoDB change streams require a replica set or sharded cluster — standalone instances do not support change streams. For MongoDB Atlas, all clusters run as replica sets by default. For self-hosted MongoDB, initialize a replica set:

Document flattening

MongoDB documents can have nested fields. Enable Flatten in your pipeline transforms to expand nested fields into top-level destination columns.

Troubleshooting

unescaped @ sign in user info — The password contains @, /, ?, or #, which break URI parsing. Encode only those as %40, %2F, %3F, %23. Example: password p@sswordmongodb+srv://user:p%40ssword@host/db. Colons and other specials do not need encoding.

Notes

  • MongoDB 4.0+ is required for change streams (CDC)
  • ObjectId fields are converted to strings
  • Arrays are serialized as JSON strings at the destination unless flattened
Last modified on August 1, 2026