MongoDB Shard Operations

Adding shards

Use admin

Add Shard Nodes , each shard is a replica set "allowlocal:true only when the Shard is configured locally , not at production"

Db.runcommand ({addshard: "localhost:9335", allowlocal:true})

Db.runcommand ({addshard: "localhost:9336", allowlocal:true})

Db.runcommand ({addshard: "localhost:9337", Allowlocal:true, "MaxSize": 20000}) Note: You can also set the size "maxSize" for different shards: 20000 (20GB)

the database to be partitioned

Db.runcommand ({enablesharding: "MyDB"})

set the collection to be fragmented : Users collection , name field key to Shard

Db.runcommand ({shardcollection: "Mydb.users", Key:{name:1}})

Db.runcommand ({shardcollection: "Mydb.users", Key:{_id:1,name:1,name:1}}) "If " errmsg ":" Please create an index t Hat starts with the Shard key before sharding. " , create an index "

View Shard Results

View partition status

Use MyDB

Db.users.getShardDistribution ()

Db.users.stats ();

Add shards to the data that is already fragmented

Db.runcommand ({addshard: "localhost:9337", allowlocal:true}) automatically balances the data

Delete Shards

Db.runcommand ({removeshard: "localhost:9335"})

Db.runcommand ({removeshard: "localhost:9336"})

Db.runcommand ({removeshard: "localhost:9337"})

"If the primary node is deleted, you also need to"

Db.runcommand ({"Moveprimary": "MyDB", "to": "localhost:9336"})

"The Db.runcommand ({removeshard:" Localhost:xxxx "}) will need to be executed once after deletion in order to completely delete the"

"Observe the deletion:"

Use admin

Db.printshardingstatus ()

"You cannot delete all shards in this way, and the last shard cannot be deleted."