checkMetadataConsistency (database command数据库命令)

Definition定义

checkMetadataConsistency

Performs a series of consistency checks on sharding metadata for a cluster, database, or collection. The command returns a cursor with either all or a batch of the inconsistency results found.对集群、数据库或集合的分片元数据执行一系列一致性检查。该命令返回一个游标，其中包含所有或一批发现的不一致结果。

Tip

In mongosh, this command can also be run through the db.checkMetadataConsistency(), db.collection.checkMetadataConsistency(), or sh.checkMetadataConsistency() helper methods.在mongosh中，此命令也可以通过db.checkMetadataConsistency()、db.collection.checkMetadataConsistency()或sh.checkMetadataConsistency()辅助方法运行。

Helper methods are convenient for mongosh users, but they may not return the same level of information as database commands. In cases where the convenience is not needed or the additional return fields are required, use the database command.助手方法对mongosh用户来说很方便，但它们可能不会返回与数据库命令相同级别的信息。如果不需要便利性或需要额外的返回字段，请使用database命令。

Run this command after major maintenance operations, such as upgrades and downgrades, to check the state of the catalog.在主要维护操作（如升级和降级）后运行此命令，以检查目录的状态。

By default, the command does not check indexes for consistency across the shards. To check indexes, set the checkIndexes option.默认情况下，该命令不会检查分片之间的索引一致性。要检查索引，请设置checkIndexes选项。

New in version 7.0.在版本7.0中新增。

Compatibility兼容性

This command is available in deployments hosted in the following environments:此命令在以下环境中托管的部署中可用：

• MongoDB Atlas: The fully managed service for MongoDB deployments in the cloud：云中MongoDB部署的完全托管服务

• MongoDB Enterprise: The subscription-based, self-managed version of MongoDB：MongoDB的基于订阅的自我管理版本
• MongoDB Community: The source-available, free-to-use, and self-managed version of MongoDB：MongoDB的源代码可用、免费使用和自我管理版本

Syntax语法

• To check the entire cluster for sharding metadata inconsistencies, run the command from the admin database.要检查整个集群是否存在分片元数据不一致，请从admin数据库运行该命令。

  db.adminCommand( {
     checkMetadataConsistency: 1
  } )

• To check the database for sharding metadata inconsistencies, run the command from the database context:要检查数据库是否存在分片元数据不一致，请从数据库上下文运行以下命令：

  use cars
  db.runCommand( {
     checkMetadataConsistency: 1
  } )

• To check a collection for sharding metadata inconsistencies, run the command with the collection name:要检查集合是否存在分片元数据不一致，请使用集合名称运行命令：

  use library
  db.runCommand( {
     checkMetadataConsistency: "authors",
  } )

Behavior行为

var cur = db.runCommand( {
   checkMetadataConsistency: 1,
   cursor: {
      batchSize: 10
   }
} )

db.runCommand( {
   checkMetadataConsistency: 1,
   checkIndexes: true
} )

Example示例

Use runCommand() to run the checkMetadataConsistency command:使用runCommand()运行checkMetadataConsistency命令：

db.runCommand( { checkMetadataConsistency: 1 } )

Example Output:输出示例：

{
   cursor: {
      id: Long("0"),
      ns: "test.$cmd.aggregate",
      firstBatch: [
         {
            type: "MisplacedCollection",
            description: "Unsharded collection found on shard different from database primary shard",
            details: {
               namespace: "test.authors",
               shard: "shard02",
               localUUID: new UUID("1ad56770-61e2-48e9-83c6-8ecefe73cfc4")
            }
         }
      ],
   },
   ok: 1
}