addShardToZone
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Definition
addShardToZone
New in version 3.4.
Associates a shard with a zone. MongoDB associates this shard with the given zone. Chunks that are covered by the zone are assigned to shards associated with the zone.
Tip
In the
mongo
Shell, this command can also be run through thesh.addShardToZone()
helper method.Helper methods are convenient for
mongo
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.
Syntax
You can only run addShardToZone
on the admin
database
from a mongos
instance.
The addShardToZone
command has the following syntax:
db.adminCommand( { addShardToZone: <string>, zone: <string> } )
Fields
The command takes the following fields:
Field | Type | Description |
---|---|---|
string | The name of the shard to associate with the zone. | |
string | The name of the zone to associate with the shard. |
The mongo
shell provides the helper method
sh.addShardToZone()
Behavior
You can associate a zone with multiple shards, and a shard can associate with multiple zones.
See the zone manual page for more information on zones in a sharded cluster.
Ranges
MongoDB effectively ignores zones that do not have at least one range of shard key values associated with it.
To associate a range of shard key values with a zone, use the
updateZoneKeyRange
database command, or the
sh.updateZoneKeyRange()
shell helper.
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.
Security
For sharded clusters that enforce access control, you must authenticate as a user whose privileges include either:
update
on theshards
collection in theconfig
database; or, alternatively,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 addShardToZone
. See the
documentation page for Role-Based Access Control for
more information.
Example
The following example associates shard0000
with zone JFK
:
db.adminCommand( { addShardToZone : "shard0000" , zone : "JFK" } )
A shard can associate with multiple zones. The following example associates
LGA
to shard0000
:
db.adminCommand( { addShardToZone : "shard0000" , zone : "LGA" } )
shard0000
associates with both the LGA
zone and the JFK
zone. In a
balanced cluster, MongoDB routes reads and writes covered by either zone to
shard0000
.