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MongoDB Manual

Use Database Commands

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  • Database Command Form
  • Issue Commands
  • admin Database Commands
  • Command Responses

The MongoDB command interface provides access to all non CRUD database operations. Fetching server statistics, initializing a replica set, and running an aggregation pipeline or map-reduce job are all accomplished with commands.

See Database Commands for list of all commands sorted by function.

You specify a command first by constructing a standard BSON document whose first key is the name of the command. For example, specify the hello command using the following BSON document:

{ hello: 1 }

mongosh provides a helper method for running commands called db.runCommand(). The following operation in mongosh runs the previous command:

db.runCommand( { hello: 1 } )

Many Drivers provide an equivalent for the db.runCommand() method. Internally, running commands with db.runCommand() is equivalent to a special query against the $cmd collection.

Many common commands have their own shell helpers or wrappers in mongosh and drivers, such as the db.hello() method in mongosh.

You can use the maxTimeMS option to specify a time limit for the execution of a command, see Terminate a Command for more information on operation termination.

You must run some commands on the admin database. Normally, these operations resemble the following:

use admin
db.runCommand( {buildInfo: 1} )

However, there's also a command helper that automatically runs the command in the context of the admin database:

db.adminCommand( {buildInfo: 1} )

For all commands, MongoDB returns a response document that contains the following fields:

<command result>
Result fields specific to the command that ran.
A number that indicates if the command succeeded (1) or failed (0).

The logical time of the operation. MongoDB uses the logical time to order operations. Only for replica sets and sharded clusters.

If the command does not generate an oplog entry, for example, a read operation, then the operation does not advance the logical clock. In this case, operationTime returns:

For operations associated with causally consistent sessions, the MongoDB drivers use the logical time to automatically set the Read Operations and afterClusterTime period.


A document that returns the signed cluster time. Cluster time is a logical time used for ordering of operations. Only for replica sets and sharded clusters. For internal use only.

The document contains the following fields:

  • clusterTime: timestamp of the highest known cluster time for the member.

  • signature: a document that contains the hash of the cluster time and the id of the key used to sign the cluster time.


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