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Monitor MongoDB change streams

Watch live insert, update, replace, and delete events in a bounded in-memory monitor without creating a durable consumer.

The Change Stream Monitor shows live collection events for debugging and operational verification. It is intentionally ephemeral. Events and resume tokens are never stored.

mongoui Change Stream Monitor showing live insert, update, replace, and delete events
The bounded monitor displays live collection events and retains them only in memory.

Start a monitor

  1. Connect to a replica set or sharded deployment.
  2. Open Tools, then Change stream monitor.
  3. Select the database and collection.
  4. Choose insert, update, replace, and delete event types.
  5. Optionally enable Look up the current document for updates.
  6. Choose Start.

Standalone MongoDB servers do not support change streams. The app reports the topology requirement and leaves Start disabled.

Choose whether updates need a full document

By default, update events carry the changed field delta that MongoDB emits. Enabling current-document lookup requests fullDocument: "updateLookup". That performs an additional lookup and returns the latest majority-committed document available when the event is processed, not necessarily the document exactly as it looked at the instant of the update.

Leave lookup off when deltas are enough. It reduces database work and avoids showing a current document whose later changes have already moved past the event.

The monitor is bounded and disposable

The renderer keeps the newest 200 events. When more arrive, the oldest visible events are dropped and the counter reports how many left the buffer. Oversized value-bearing payloads are omitted instead of expanding memory without a limit.

Choose Stop to close the driver stream. Navigation, disconnect, window closure, and renderer destruction close it too. Clear removes visible events but does not alter MongoDB.

An invalidate event ends the stream. Refresh the catalog and start a new monitor after the collection is dropped, renamed, or otherwise invalidated. Unexpected server completion is shown as ended rather than pretending the monitor is still listening.

Because resume tokens are not persisted, this tool is a debugger, not an event-processing service. Use an application-owned durable consumer when every event must be processed.

See debug MongoDB change streams for event semantics and production tradeoffs.