Move a Collection移动集合

Move the collection.移动集合。

To move an unsharded collection named inventory on the app database to the shard02 shard, run moveCollection:要将app数据库上名为inventory的未分片集合移动到shard02分片，请运行moveCollection：

db.adminCommand(
  {
    moveCollection: "app.inventory",
    toShard: "shard02"
  }
)

To get a list of the available shard IDs, run sh.status(). For details, see sh.status() Output.要获取可用分片ID的列表，请运行sh.status()。有关详细信息，请参阅sh.status()输出。

Monitor the progress of the moveCollection operation.监视moveCollection操作的进度。

1. Monitor the time remaining.监控剩余时间。

   To monitor the time remaining for the moveCollection operation, use the $currentOp pipeline stage.要监视moveCollection操作的剩余时间，请使用$currentOp管道阶段。

   This example shows how to check the progress of moveCollection on the app.inventory collection:此示例显示了如何检查app.inventory集合上moveCollection的进度：

   db.getSiblingDB("admin").aggregate( [
      { $currentOp: { allUsers: true, localOps: false } },
      {
         $match: {
         type: "op",
         "originatingCommand.reshardCollection": "app.inventory"
         }
      }
   ] )

   Note

   To see updated values, you need to continuously run the preceeding pipeline.要查看更新的值，您需要连续运行前面的管道。

   The $currentOp pipeline outputs:$currentOp管道输出：

   • totalOperationTimeElapsedSecs: elapsed operation time in seconds：运行时间（秒）
   • remainingOperationTimeEstimatedSecs: estimated time remaining in seconds for the current moveCollection operation. It is returned as -1 when a new moveCollection operation starts.：当前moveCollection操作的估计剩余时间（秒）。当新的moveCollection操作开始时，它将返回-1。

   Note

   remainingOperationTimeEstimatedSecs is set to a pessimistic time estimate:设置为悲观时间估计：

   • The catch-up phase time estimate is set to the clone phase time, which追赶阶段时间估计值设置为克隆阶段时间

     is a relatively long time.这是一个相对较长的时间。

   • In practice, if there are only a few pending write operations, the在实践中，如果只有少数未决的写入操作

     actual catch-up phase time is relatively short.实际追赶阶段时间相对较短。

   This pipeline stage has output similar to the following:该管道阶段的输出类似于以下内容：

   [
      {
         shard: '<shard>',
         type: 'op',
         desc: 'ReshardingRecipientService | ReshardingDonorService | ReshardingCoordinatorService <reshardingUUID>',
         op: 'command',
         ns: '<database>.<collection>',
         originatingCommand: {
         reshardCollection: '<database>.<collection>',
         key: <shardkey>,
         unique: <boolean>,
         collation: { locale: 'simple' }
         },
         totalOperationTimeElapsedSecs: <number>,
         remainingOperationTimeEstimatedSecs: <number>,
         ...
      },
      ...
   ]

2. Monitor the number of bytes transferred.监控传输的字节数。

   To monitor the number of bytes transferred, use shardingStatistics.resharding.active.bytesCopied and compare against the number of bytes in the collection.要监视传输的字节数，请使用shardingStatistics.resharding.active.bytesCopied并与集合中的字节数进行比较。

Confirm the collection has been moved.确认集合已移动。

To confirm the collection has been moved to the expected shard, use the $collStats pipeline stage.要确认集合已移动到预期的分片，请使用$collStats管道阶段。

This example shows how to confirm that the app.inventory collection exists on the expected shard:此示例显示了如何确认app.inventory集合存在于预期的分片上：

db.inventory.aggregate( [
  { $collStats: {} },
  { $project: { "shard": 1 } }
] )

This pipeline stage has output similar to the following:该管道阶段的输出类似于以下内容：

[ { shard: 'shard02' } ]