sh.balancerCollectionStatus()
Definition
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.
Compatibility
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.
MongoDB Enterprise: The subscription-based, self-managed version of MongoDB
MongoDB Community: The source-available, free-to-use, and self-managed version of MongoDB
Syntax
The sh.balancerCollectionStatus()
has the following form:
sh.balancerCollectionStatus( <namespace> )
Parameter
The sh.balancerCollectionStatus()
method takes the following parameter:
Access Control
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.
Examples
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) } } }
Ongoing Defragmentation Process
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.