deleteShard

項目一覧

定義
互換性
構文
動作
例

定義

removeShard: Removes a shard from a シャーディングされたクラスター. When you run removeShard, MongoDB drains the shard by using the balancer to move the shard's chunks to other shards in the cluster. Once the shard is drained, MongoDB removes the shard from the cluster.
注意
If you want to re-add a removed shard to your sharded cluster, you must clear the storage.dbPath of all the nodes of the shard to remove the shard's files of before you can re-add it.

互換性

このコマンドは、次の環境でホストされている配置で使用できます。

MongoDB Enterprise: サブスクリプションベースの自己管理型 MongoDB バージョン
MongoDB Community: ソースが利用可能で、無料で使用できる自己管理型の MongoDB のバージョン

注意

This command is not supported in MongoDB Atlas. See Modify your Atlas Sharded Cluster to add or remove shards from your Atlas cluster,

構文

このコマンドの構文は、次のとおりです。

db.adminCommand(
   {
     removeShard : <shardToRemove>
   }
)

動作

No Cluster Back Ups During Shard Removal

You cannot back up the cluster data during shard removal.

Concurrent `removeShard` Operations

You can have more than one removeShard operation in progress.

Access Requirements

If you have authorization enabled, you must have the clusterManager role or any role that includes the removeShard action.

Database Migration Requirements

Each database in a sharded cluster has a primary shard. If the shard you want to remove is also the primary of one of the cluster's databases, then you must manually move the databases to a new shard after migrating all data from the shard. See the movePrimary command and the シャーディングされたクラスターからシャードを削除する for more information.

Chunk Balancing

チャンクの分布が不均一なクラスター内のシャードを削除すると、バランサーはまずドレインシャードからチャンクを削除し、次に残りの不均一なチャンクの分布のバランスをとります。

以下も参照してください。

balancerCollectionStatus

書込み保証 (write concern)

mongos converts the 書込み保証 (write concern) of the removeShard command to "majority".

変更ストリーム

シャードを削除すると、開いている変更ストリームのカーソルが閉じてしまい、閉じた変更ストリームのカーソルが完全に再開できなくなることがあります。

DDL 操作

クラスターが DDL操作（ reshardCollectionなどのコレクションを変更する操作）を実行しているときにremoveShardを実行すると、 removeShardは同時 DDL操作が完了した後にのみ実行されます。

例

From mongosh, the removeShard operation resembles the following:

db.adminCommand( { removeShard : "bristol01" } )

置換 bristol01 with the name of the shard to remove. When you run removeShard, the command returns with a message that resembles the following:

{
   "msg" : "draining started successfully",
   "state" : "started",
   "shard" : "bristol01",
   "note" : "you need to drop or movePrimary these databases",
   "dbsToMove" : [
      "fizz",
      "buzz"
   ],
   "ok" : 1,
   "operationTime" : Timestamp(1575398919, 2),
   "$clusterTime" : {
      "clusterTime" : Timestamp(1575398919, 2),
      "signature" : {
         "hash" : BinData(0,"Oi68poWCFCA7b9kyhIcg+TzaGiA="),
         "keyId" : NumberLong("6766255701040824328")
      }
   }
}

The balancer begins migrating ("draining") chunks from the shard named bristol01 to other shards in the cluster. These migrations happen slowly in order to avoid placing undue load on the cluster.

The output includes the field dbsToMove indicating the databases for which bristol01 is the プライマリシャード. After the balancer moves all chunks and after all collections are moved by moveCollection, you must movePrimary for the database(s).

If you run the command again, removeShard returns the current status of the process. For example, if the operation is in an ongoing state, the command returns an output that resembles the following:

{
   "msg" : "draining ongoing",
   "state" : "ongoing",
   "remaining" : {
      "chunks" : NumberLong(2),
      "dbs" : NumberLong(2),
      "jumboChunks" : NumberLong(0)
   },
   "note" : "you need to drop or movePrimary these databases",
   "dbsToMove" : [
      "fizz",
      "buzz"
   ],
   "ok" : 1,
   "operationTime" : Timestamp(1575399086, 1655),
   "$clusterTime" : {
      "clusterTime" : Timestamp(1575399086, 1655),
      "signature" : {
         "hash" : BinData(0,"XBrTmjMMe82fUtVLRm13GBVtRE8="),
         "keyId" : NumberLong("6766255701040824328")
      }
   }
}

In the output, the remaining field includes the following fields:

フィールド	説明
`chunks`	Total number of chunks currently remaining on the shard.
`dbs`	Total number of databases whose プライマリシャード is the shard. These databases are specified in the `dbsToMove` output field.
`jumboChunks`	`chunks`の合計数のうち、ジャンボである数値。 If the `jumboChunks` is greater than 0, wait until only the `jumboChunks` remain on the shard. Once only the jumbo chunks remain, you must manually clear the jumbo flag before the draining can complete. See `jumbo` Flag. `jumbo`フラグがクリアされると、バランサーはこれらのチャンクを移行できます。移行手順の詳細については、「範囲の移行手順」を参照してください。

Continue checking the status of the removeShard command (i.e. rerun the command) until the number of chunks remaining is 0.

{
   "msg" : "draining ongoing",
   "state" : "ongoing",
   "remaining" : {
      "chunks" : NumberLong(0),             // All chunks have moved
      "dbs" : NumberLong(2),
      "jumboChunks" : NumberLong(0)
   },
   "note" : "you need to drop or movePrimary these databases",
   "dbsToMove" : [
      "fizz",
      "buzz"
   ],
   "ok" : 1,
   "operationTime" : Timestamp(1575400343, 1),
   "$clusterTime" : {
      "clusterTime" : Timestamp(1575400343, 1),
      "signature" : {
         "hash" : BinData(0,"9plu5B/hw4uWAgEmjjBP3syw1Zk="),
         "keyId" : NumberLong("6766255701040824328")
      }
   }
}

After all chunks have been drained from the shard, if you have dbsToMove, you can either movePrimary for those databases or alternatively, drop the databases (which deletes the associated data files).

After the balancer completes moving all chunks off the shard and you have handled the dbsToMove, removeShard can finish. Running removeShard again returns output that resembles the following:

{
   "msg" : "removeshard completed successfully",
   "state" : "completed",
   "shard" : "bristol01",
   "ok" : 1,
   "operationTime" : Timestamp(1575400370, 2),
   "$clusterTime" : {
      "clusterTime" : Timestamp(1575400370, 2),
      "signature" : {
         "hash" : BinData(0,"JjSRciHECXDBXo0e5nJv9mdRG8M="),
         "keyId" : NumberLong("6766255701040824328")
      }
   }
}

戻る

refineCollectionShardKey

deleteShardFromZone