Change Events
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Change streams watch collections, databases, or deployments for changes.
When a change occurs on a watched resource, the change stream returns a change event notification document, with information on the operation and the changes it made.
Operation Types
Event | Description |
---|---|
Occurs on the creation of a collection. Requires that you set the showExpandedEvents option to New in version 6.0. | |
Occurs on the creation of indexes on the collection. Requires that you set the showExpandedEvents option to New in version 6.0. | |
Occurs when a document is removed from the collection. | |
Occurs when a collection is dropped from a database. | |
Occurs when a database is dropped. | |
Occurs when an index is dropped from the collection. Requires that you set the showExpandedEvents option to New in version 6.0. | |
Occurs when an operation adds documents to a collection. | |
Occurs when an operation renders the change stream
invalid. | |
Occurs when a collection is modified. Requires that you set the showExpandedEvents option to New in version 6.0. | |
Occurs when a collection is renamed. | |
Occurs when an update operation removes a document from
a collection and replaces it with a new document. | |
Occurs when the shard key for a collection and the distribution of data changes. Requires that you set the showExpandedEvents option to New in version 6.1: (Also available in 6.0.14) | |
Occurs when a collection is sharded. Requires that you set the showExpandedEvents option to New in version 6.0. | |
Occurs when an operation updates a document in a collection. |
Resume Token
Each change event includes an _id
field, which contain a document. This
document can serve as the resume token when
starting a change stream.
Expanded Events
New in version 6.0.
Starting in MongoDB 6.0, change streams support change notifications for DDL
events, like the createIndexes and
dropIndexes events. To include expanded
events in a change stream, create the change stream cursor using the
showExpandedEvents
option.
For example:
let cur = db.names.aggregate( [ { $changeStream: { showExpandedEvents: true } } ] ) cur.next()