refineCollectionShardKey Event

Summary

refineCollectionShardKey: New in version 6.0.
A refineCollectionShardKey event occurs when a collection's shard key is modified.

Description

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 fields within the `_id` object depend on the MongoDB versions and, in some cases, the feature compatibility version (FCV) at the time of the change stream's opening or resumption. For an example of resuming a change stream by `resumeToken`, see Resume a Change Stream.
`clusterTime`	Timestamp	`clusterTime` is the timestamp from the oplog entry associated with the event. Due to oplog size limits, multi-document transactions may create multiple oplog entries. In a transaction, change stream events staged in a given oplog entry share the same `clusterTime`. Events with the same `clusterTime` may not all relate to the same transaction. Some events don't relate to a transaction at all. Starting in MongoDB 8.0, this may be true for events on any deployment. In previous versions, this behavior was possible only for events on a sharded cluster. To identify events for a single transaction, you can use the combination of `lsid` and `txnNumber` in the change stream event document. Changed in version 8.0.
`collectionUUID`	UUID	UUID identifying the collection where the change occurred. New in version 6.0.
`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.
`operationDescription`	Document	Additional information on the change operation. This document and its subfields only appears when the change stream uses expanded events. New in version 6.0.
`operationDescription.` `shardKey`	Document	The shard key for the collection where the change occurred. New in version 6.0.
`operationDescription.` `oldShardKey`	Document	The shard key for the collection that changed. New in version 6.1.

Example

The following example shows a refineCollectionShardKey event:

{
   "_id": { <ResumeToken> },
   "operationType": "refineCollectionShardKey",
   "clusterTime": Timestamp({ t: 1654894852, i: 52 }),
   "collectionUUID": UUID("98046a1a-b649-4e5b-9c75-67594221ce19"),
   "ns": {"db": "reshard_collection_event", "coll": "coll"},
   "operationDescription": {
     "shardKey": {"_id": 1, akey: 1},
     "oldShardKey": {"_id": 1}
   }
}

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