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An insert event occurs when an operation adds documents to a collection.


Field Type Description
_id Document

A BSON object which serves as an identifier for the change stream event. This value is used as the resumeToken for the resumeAfter parameter when resuming a change stream. The _id object has the following form:

   "_data" : <BinData|hex string>

The _data type depends on the MongoDB versions and, in some cases, the feature compatibility version (FCV) at the time of the change stream’s opening or resumption. See Resume Tokens for the full list of _data types.

For an example of resuming a change stream by resumeToken, see Resume a Change Stream.

clusterTime Timestamp

The timestamp from the oplog entry associated with the event.

Change stream event notifications associated with a multi-document transaction all have the same clusterTime value: the time when the transaction was committed.

On sharded clusters, events with the same clusterTime may not all relate to the same transaction. Some events don’t relate to a transaction at all.

To identify events for a single transaction, you can use the combination of lsid and txnNumber in the change stream event document.

New in version 4.0.

documentKey document

Document that contains the _id value of the document created or modified by the CRUD operation.

For sharded collections, this field also displays the full shard key for the document. The _id field is not repeated if it is already a part of the shard key.

fullDocument document The document created by the operation.
lsid document

The identifier for the session associated with the transaction.

Only present if the operation is part of a multi-document transaction.

New in version 4.0.

ns document

The namespace (database and or collection) affected by the event.

ns.coll string

The name of the collection where the event occurred.

ns.db string

The name of the database where the event occurred.

operationType string

The type of operation that the change notification reports.

Returns a value of insert for these change events.

txnNumber NumberLong

Together with the lsid, a number that helps uniquely identify a transction.

Only present if the operation is part of a multi-document transaction.

New in version 4.0.


The following example illustrates an insert event:

   "_id": { <Resume Token> },
   "operationType": "insert",
   "clusterTime": <Timestamp>,
   "ns": {
      "db": "engineering",
      "coll": "users"
   "documentKey": {
      "userName": "alice123",
      "_id": ObjectId("599af247bb69cd89961c986d")
   "fullDocument": {
      "_id": ObjectId("599af247bb69cd89961c986d"),
      "userName": "alice123",
      "name": "Alice"

The documentKey field includes both the _id and the userName field. This indicates that the engineering.users collection is sharded, with a shard key on userName and _id.

The fullDocument document represents the version of the document at the time of the insert.

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