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sh.updateZoneKeyRange()¶
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Definition¶
-
sh.
updateZoneKeyRange
(namespace, minimum, maximum, zone)¶ New in version 3.4.
Associates a range of shard key values with a zone.
Starting in MongoDB 4.0.2, you can run
updateZoneKeyRange
database command and its helperssh.updateZoneKeyRange()
andsh.addTagRange()
on an unsharded collection or a non-existing collection.Important
mongo
Shell MethodThis page documents a
mongo
method. This is not the documentation for database commands or language-specific drivers, such as Node.js. To use the database command, see theupdateZoneKeyRange
command.For MongoDB API drivers, refer to the language-specific MongoDB driver documentation.
sh.updateZoneKeyRange()
takes the following arguments:Parameter Type Description namespace
string The namespace of the sharded collection associate with the
zone
.The collection must be sharded for the operation to succeed.
minimum
document The inclusive lower bound of the range of shard key values.
Specify each field of the shard key in the form of
<fieldname> : <value>
. The value must be of the same BSON type or types as the shard key.maximum
document The exclusive upper bound of the range of shard key values.
Specify each field of the shard key in the form of
<fieldname> : <value>
. The value must be of the same BSON type or types as the shard key.zone
string The name of the zone to associate with the range of shard key values bounded by minimum
andmaximum
.Only issue
sh.updateZoneKeyRange()
when connected to amongos
instance.
Behavior¶
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.
See the zone manual page for more information on zones in sharded clusters.
Initial Chunk Distribution¶
Starting in MongoDB 4.0.2, you can run
updateZoneKeyRange
database command and its helpers
sh.updateZoneKeyRange()
and sh.addTagRange()
on
an unsharded collection or a non-existing collection.
Tip
Changed in version 4.0.3: By defining the zones and the zone ranges before sharding an empty or a non-existing collection, the shard collection operation creates chunks for the defined zone ranges as well as any additional chunks to cover the entire range of the shard key values and performs an initial chunk distribution based on the zone ranges. This initial creation and distribution of chunks allows for faster setup of zoned sharding. After the initial distribution, the balancer manages the chunk distribution going forward.
See Pre-Define Zones and Zone Ranges for an Empty or Non-Existing Collection for an example.
Balancer¶
After associating 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. See Balancer for more information.
See the sharded cluster balancer manual page 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 (available starting in version 4.2.2, 4.0.14, 3.6.16).
The clusterAdmin
or clusterManager
built-in roles have
the appropriate permissions for issuing sh.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:
The following operation removes the previously created range by passing
null
to the zone
field.
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:
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:
Pre-Define Zones and Zone Ranges for an Empty or Non-Existing Collection¶
Starting in MongoDB 4.0.2, you can run
updateZoneKeyRange
database command and its helpers
sh.updateZoneKeyRange()
and sh.addTagRange()
on
an unsharded collection or a non-existing collection.
By defining the zones and the zone ranges before sharding an empty or a non-existing collection, the shard collection operation creates chunks for the defined zone ranges as well as any additional chunks to cover the entire range of the shard key values and performs an initial chunk distribution based on the zone ranges. This initial creation and distribution of chunks allows for faster setup of zoned sharding. After the initial distribution, the balancer manages the chunk distribution going forward.
First, use sh.addShardToZone()
to create the zones:
Then, use sh.updateZoneKeyRange()
to create the ranges:
If you haven’t enabled sharding for exampledb
, use
sh.enableSharding()
to enable sharding for the database:
Finally, use sh.shardCollection()
to shard the collection contacts
:
Note
If the collection does not exist, the sharding operation creates the collection.
To see the created chunks and distribution, run the
sh.status()
operation:
The method returns:
For the collection, sharding operation created 5 chunks (two chunks that correspond to the zone ranges and the other three to cover all other values) across shardA and shardB.
See also