HiddenShardedCollection

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Description

Format
Example

Description

HiddenShardedCollection: A collection is registered in the config.collections cluster catalog under a non-existent database.
New in version 7.0.

Format

{
   type: "HiddenShardedCollection",
   description: "<string>",
   details: {
      namespace: "<string>",
      collection: "<object>",
   }
}

HiddenShardedCollection inconsistency documents contain the following fields:

Field	Type	Description
`type`	string	Type of inconsistency document. Returns a value of `HiddenShardedCollection` for this inconsistency type.
`description`	string	Describes the nature of the inconsistency found in the metadata.
`details`	document	Document with additional information on where the inconsistency exists in the database and sharded cluster.
`details.namespace`	string	Indicates the database and collection where the inconsistency exists.
`details.collection`	document	Information about the collection.

Example

Use the db.adminCommand() method to call the checkMetadataConsistency command:

db.adminCommand( { checkMetadataConsistency: 1 } )

The method returns a cursor with a batch of documents showing the inconsistencies found in the sharding metadata. The example below shows a cursor with a HiddenShardedCollection inconsistency document:

{
   cursor: {
      id: Long("0"),
      ns: "test.$cmd.aggregate",
      firstBatch: [
         {
            type: "HiddenShardedCollection",
            description: "Found sharded collection but relative database does not exist",
            details: {
               namespace: "test.authors",
               collection: {
                   _id: "test.authors",
                   lastmodEpoch: ObjectId("64ddd78de906038182671674"),
                   lastmod: ISODate("2023-08-17T08:17:17.944Z"),
                   timestamp: Timestamp(1692260237, 58),
                   uuid: new UUID("69317741-7bc5-4eca-8877-7858cecf67d6"),
                   key: {
                      "skey" : 1
                   },
                   unique: false,
                   noBalance: false
                }
            }
         }
      ],
   },
   ok: 1
}

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