Find a Shard Key查找分片键

Every shared collection has a shard key. 每个共享集合都有一个分片键。To display the shard key, connect to a mongos instance and run the db.printShardingStatus() method:要显示分片键，请连接到mongos实例并运行db.printShardingStatus()方法：

db.printShardingStatus()

The output resembles:输出类似于：

<dbname>.<collection>
   shard key: { <shard key> : <1 or hashed> }
   unique: <boolean>
   balancing: <boolean>
   chunks:
      <shard name1> <number of chunks>
      <shard name2> <number of chunks>
      ...
   { <shard key>: <min range1> } -->> { <shard key> : <max range1> } on : <shard name> <last modified timestamp>
   { <shard key>: <min range2> } -->> { <shard key> : <max range2> } on : <shard name> <last modified timestamp>
   ...
   tag: <tag1>  { <shard key> : <min range1> } -->> { <shard key> : <max range1> }
   ...

For more details on the db.printShardingStatus() output, see the sharded collection section on the sh.status() page.有关db.printShardingStatus()输出的更多详细信息，请参阅sh.status()页面上的分片集合部分。