updateZoneKeyRange
Definition
updateZoneKeyRange
The
updateZoneKeyRange
administrative command can either create or remove the association between a range of shard key values and a zone.You can run
updateZoneKeyRange
database command and its helperssh.updateZoneKeyRange()
andsh.addTagRange()
on an unsharded collection or a non-existing collection.Tip
In
mongosh
, this command can also be run through thesh.updateZoneKeyRange()
helper method.Helper methods are convenient for
mongosh
users, but they may not return the same level of information as database commands. In cases where the convenience is not needed or the additional return fields are required, use the database command.To run
updateZoneKeyRange
, use thedb.runCommand( { <command> } )
method.You must run
addShardToZone
on the admin database.
Compatibility
This command 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 serverless instances. 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 command has the following syntax:
db.adminCommand( { updateZoneKeyRange: <string>, min: <document>, max: <document>, zone: <string> | <null> } )
Command Fields
The command takes the following fields:
Parameter | Type | Description |
---|---|---|
updateZoneKeyRange | string | The namespace of the collection to associate with the range. The collection must be sharded for the command to succeed. |
min | document | The inclusive lower bound of the range of shard key values. Specify each field of the shard key in the form of To use hashed sharding, the field value of |
max | document | The exclusive upper bound of the range of shard key values. Specify each field of the shard key in the form of To use hashed sharding, the field value of |
zone | string | The name of the zone to associate with the range bounded by the
If the value does not match an existing zone, the command fails. Specify |
Behavior
If no zone range matches the minimum and maximum bounds passed to
updateZoneKeyRange
, nothing is removed.
Only issue updateZoneKeyRange
when connected to a
mongos
instance.
mongosh
provides two helper methods:
sh.updateZoneKeyRange()
for adding a range of shard key values to a zone.sh.removeRangeFromZone()
for removing a range of shard key values from a zone.
You cannot create a range of shard key values whose lower and upper boundaries
overlap with an existing range for the sharded collection. For example, given
an existing range of 1
to 10
, you cannot create a new range of 5
to 20
, as the new range would overlap with the existing range.
A zone can have multiple ranges of data associated with it, but a range can at most be associated with a single zone.
When removing the association between a range and a zone,
updateZoneKeyRange
does not remove the zone. Use the
removeShardFromZone
command to remove the association between a
zone and a shard.
See the zone manual page for more information on zones in sharded clusters.
Initial Chunk Distribution for Empty or Non-Existing Collections
If you are considering performing zone sharding
on an empty or non-existent collection, use
updateZoneKeyRange
to create the zones and zone ranges
before sharding the collection (since 4.0.2). Starting in version
4.0.3, creating zones and zone ranges on empty or non-existing
collections allows MongoDB to optimize the initial chunk creation and
distribution process when sharding the collection. This optimized
process supports faster setup of zoned sharding with less balancer
overhead than creating zones after sharding. The balancer performs all chunk management after the optimized
initial chunk creation and distribution.
For an example of defining zones and zone ranges for initial chunk distribution, see Pre-Define Zones and Zone Ranges for an Empty or Non-Existing Collection.
Initial Chunk Distribution with Compound Hashed Shard Keys
MongoDB supports sharding collections on compound hashed indexes. MongoDB can perform optimized initial chunk creation and distribution when sharding the empty or non-existing collection on a compound hashed shard key.
If the hashed field is the prefix of the shard key (i.e. the first field in the shard key), all of the following must be true for MongoDB to perform initial chunk creation and distribution:
The collection has a single zone range with
MinKey
for all lower-bound fields andMaxKey
for all upper-bound fields.sh.shardCollection()
specifies the presplitHashedZones: true option.
If the hashed field is not the prefix of the shard key (i.e. the shard key has one or more non-hashed leading fields), all of the following must be true for MongoDB to perform initial chunk creation and distribution:
The collection has one zone range for each combination of distinct prefix field values (i.e. all fields preceding the hashed field).
For the lower-bound of each zone range, specify
MinKey
for the hashed field and all subsequent fields.For each zone range, at least one upper-bound prefix field must differ from its lower-bound counterpart.
sh.shardCollection()
specifies the presplitHashedZones: true option.
For a more complete example of defining zones and zone ranges for initial chunk distribution on a compound hashed shard key, see Pre-Define Zones and Zone Ranges for an Empty or Non-Existing Collection.
Balancer
After successfully running updateZoneKeyRange
, there may be chunk
migrations during the next balancer round.
After adding a range to a zone, the balancer must first run in order to migrate any chunks whose ranges are covered by the zone to shards inside of that zone. Until balancing completes, some chunks may reside on the wrong shard given the configured zones for the sharded cluster.
Removing the association between a range and a zone removes the constraints keeping chunks covered by the range on the shards inside that zone. During the next balancer round, the balancer may migrate chunks that were previously covered by the zone.
See the documentation for the sharded cluster balancer for more information on how migrations work in a sharded cluster.
Bounds
Zone ranges are always inclusive of the lower boundary and exclusive of the upper boundary.
Dropped Collections
Dropping a collection deletes its associated zone/tag ranges.
In earlier versions, MongoDB does not remove the tag associations for a dropped collection, and if you later create a new collection with the same name, the old tag associations will apply to the new collection.
Security
For sharded clusters running with authentication, you must authenticate as either:
a user whose privileges include the specified actions on various collections in the
config
database:or, alternatively,
a user whose privileges include
enableSharding
on the cluster resource.
The clusterAdmin
or clusterManager
built-in roles have
the appropriate permissions for issuing updateZoneKeyRange
. See
the documentation page for Role-Based Access Control
for more information.
Example
Given a sharded collection exampledb.collection
with a shard key of { a
: 1 }
, the following operation creates a range with a lower bound of 1
and an upper bound of 10
on the alpha
zone:
admin = db.getSiblingDB("admin") admin.runCommand( { updateZoneKeyRange : "exampledb.collection", min : { a : 1 }, max : { a : 10 }, zone : "alpha" } )
The following operation removes the previously created range by passing
null
to the zone
field.
admin = db.getSiblingDB("admin") admin.runCommand( { updateZoneKeyRange : "exampledb.collection", min : { a : 1 }, max : { a : 10 }, zone : null } )
The min
and max
must match exactly the bounds of the target range.
The following operation attempts to remove the previously created range, but
specifies { a : 0 }
as the min
bound:
admin = db.getSiblingDB("admin") admin.runCommand( { updateZoneKeyRange : "exampledb.collection", min : { a : 0 }, max : { a : 10 }, zone : null } )
While the range of { a : 0 }
and { a : 10 }
encompasses the existing
range, it is not an exact match and therefore updateZoneKeyRange
does not remove anything.
Compound Shard Key
Given a sharded collection exampledb.collection
with a shard key of { a
: 1, b : 1 }
, the following operation creates a range covering the lower
bound of { a: 1, b : 1 }
and an upper bound of { a : 10, b : 10}
and
associates it with the alpha
zone:
admin = db.getSiblingDB("admin") admin.runCommand( { updateZoneKeyRange : "exampledb.collection", min : { a : 1, b : 1 }, max : { a : 10, b : 10 }, zone : "alpha" } )