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sh.balancerCollectionStatus()

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  • Definition
  • Compatibility
  • Syntax
  • Access Control
  • Examples
sh.balancerCollectionStatus(namespace)

Returns a document that contains information about whether the chunks of a sharded collection are balanced (i.e. do not need to be moved) as of the time the command is run or need to be moved because of draining shards, zone violation or imbalance of chunks across shards.

Important

mongosh Method

This page documents a mongosh method. This is not the documentation for database commands or language-specific drivers, such as Node.js.

For the database command, see the balancerCollectionStatus command.

For MongoDB API drivers, refer to the language-specific MongoDB driver documentation.

This method is available in deployments hosted in the following environments:

  • MongoDB Atlas: The fully managed service for MongoDB deployments in the cloud

Important

This command is not supported in M0, M2, and M5 clusters. For more information, see Unsupported Commands.

The sh.balancerCollectionStatus() has the following form:

sh.balancerCollectionStatus( <namespace> )

The sh.balancerCollectionStatus() method takes the following parameter:

Parameter
Type
Description
String

The namespace of the collection to shard in the form "<database>.<collection>".

When running with access control, the user must have the enableSharding privilege actions on database and/or collection to run the method. That is, a user must have a role that grants the following privilege:

{ resource: { db: <database>, collection: <collection> }, actions: [ "enableSharding" ] }

The built-in clusterManager role provides the appropriate privileges.

To check whether the chunks of a sharded collection test.contacts is currently in balance, connect to a mongos instance and issue the following:

sh.balancerCollectionStatus("test.contacts")

If the chunks for the collection do not need to be moved, the method returns an output similar to the following:

{
"balancerCompliant" : true,
"ok" : 1,
"operationTime" : Timestamp(1583193238, 1),
"$clusterTime" : {
"clusterTime" : Timestamp(1583193238, 1),
"signature" : {
"hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
"keyId" : NumberLong(0)
}
}
}

If the queried namespace is going through chunk defragmentation, the sh.balancerCollectionStatus method returns output similar to the following:

{
"chunkSize": Long("128"),
"balancerCompliant": false,
"firstComplianceViolation": "defragmentingChunks",
"details": {
"currentPhase": "moveAndMergeChunks",
"progress": { "remainingChunksToProcess": 1 }
}
}

Note

Chunk defragmentation occurs in multiple phases. The progress field only pertains to the current phase.

For the description of the output, see balancerCollectionStatus Output.

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