In sharded clusters, you can create zones that represent a group of shards and associate one or more ranges of shard key values to that zone. MongoDB routes reads and writes that fall into a zone range only to those shards inside of the zone.在分片集群中，您可以创建表示一组分片的区域，并将一个或多个分片键值范围与该区域相关联。MongoDB只将属于某个区域范围的读写路由到该区域内的那些分片。
Tip
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.通过在对空的或不存在的集合进行分片之前定义区域和区域范围，分片集合操作为定义的区域范围创建块以及任何其他块，以覆盖分片键值的整个范围，并根据区域范围执行初始块分布。这种块的初始创建和分发允许更快地设置分区分片。在初始分发之后，平衡器管理接下来的块分发。
See Pre-Define Zones and Zone Ranges for an Empty or Non-Existing Collection for an example.有关示例，请参阅空集合或不存在集合的预定义分区和分区范围。
Add Shards to a Zone将分片添加到区域
Associate a Zone with a particular shard using the sh.addShardToZone() method when connected to a mongos instance. A single shard may have multiple zones, and multiple shards may also have the same zone.
Example示例
The following example adds the zone NYC to two shards, and the zones SFO and NRT to a third shard:
sh.addShardToZone("shard0000", "NYC")
sh.addShardToZone("shard0001", "NYC")
sh.addShardToZone("shard0002", "SFO")
sh.addShardToZone("shard0002", "NRT")You may remove zone from a particular shard using the sh.removeShardFromZone() method when connected to a mongos instance, as in the following example, which removes the NRT zone from a shard:
sh.removeShardFromZone("shard0002", "NRT")Create a Zone Range
To define the zone's range of shard keys, use the sh.updateZoneKeyRange() method when connected to a mongos instance. Any given shard key range may only have one assigned zone. You cannot overlap defined ranges.
Example示例
Given a collection named users in the records database, sharded by the zipcode field. The following operations assign:
- two ranges of zip codes in Manhattan and Brooklyn the
NYCzone - one range of zip codes in San Francisco the
SFOzone
sh.updateZoneKeyRange("records.users", { zipcode: "10001" }, { zipcode: "10281" }, "NYC")
sh.updateZoneKeyRange("records.users", { zipcode: "11201" }, { zipcode: "11240" }, "NYC")
sh.updateZoneKeyRange("records.users", { zipcode: "94102" }, { zipcode: "94135" }, "SFO")Note
- Zone ranges are always inclusive of the lower boundary and exclusive of the upper boundary.
- Dropping a collection deletes its associated zone/tag ranges.
Remove a Zone Range
Use the shell helper method sh.removeRangeFromZone() to remove a range from a zone.
Example示例
The following example removes the NYC zone assignment for the range of zip codes within Manhattan:
sh.removeRangeFromZone("records.user", {zipcode: "10001"}, {zipcode: "10281"})Note
Dropping a collection deletes its associated zone/tag ranges.
View Existing Zones
Use sh.status() to list the zones associated to each shard in the cluster. You can also view a shards zones by querying the shards collection in the config database.
The following example uses the find() method to return all shards with the NYC zone.
use config
db.shards.find({ tags: "NYC" })You can find zone ranges for all namespaces in the tags collection of the config database. The output of sh.status() also displays all zone ranges.
The following example uses the find() method to return any range associated to the NYC zone.
use config
db.tags.find({ tag: "NYC" })