db.runCommand()
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Definition
db.runCommand(command, [options])Provides a helper to run specified database commands. This is the preferred method to issue database commands, as it provides a consistent interface between the shell and drivers.
ParameterTypeDescriptioncommanddocument or stringDocument or string that specifies the command. If specified as a string,db.runCommand()transforms the string into a document.optionsdocumentStarting in mongosh 2.0, options that specify howmongoshruns the command.options.readPreferenceRead preference to run the command with. If not specified, defaults to
primary.db.runCommand()ignores any other read preference global configuration set, including usingsetReadPref()or by specifyingreadPreferencein a connection string.In mongosh 1.x,
db.runCommand()does not take anoptionsargument. To set the read preference, useMongo.setReadPref()or specifyreadPreferencein the connection string.To specify a time limit in milliseconds, see Terminate Running Operations.
Behavior
db.runCommand() runs the command in the context of the
current database. Some commands are only applicable in the context of
the admin database, and you must change your db object
before running these commands or use db.adminCommand().
Read Preference
Starting in mongosh 2.0, you can specify the read preference for a
command with the options
argument. If you do not specify a read preference, db.runCommand()
defaults to primary.
Warning
In mongosh 2.0, db.runCommand() ignores any other read preference
global configuration set, including using Mongo.setReadPref() or
by specifying readPreference in a connection string.
In mongosh 1.x, db.runCommand() does not take an options
argument. db.runCommand() uses the read preference specified either
by using Mongo.setReadPref() or by specifying readPreference in
the connection string.
Examples
The following examples show how to use db.runCommand() to run
database commands.
hello Command Without Specified Read Preference
This example shows how to use db.runCommand() to run the
hello command.
db.runCommand( { hello: 1 } )
For details on output, see hello Output.
For details on read preference behavior, see Read Preference.
hello Command with readPreference: secondaryPreferred
This example shows how to use db.runCommand() to run the
hello command with the secondaryPreferred
read preference.
db.runCommand( { hello: 1 }, { readPreference: "secondaryPreferred" } )
For details on output, see hello Output.
For details on read preference behavior, see Read Preference.
Response
The method returns a response document that contains the following fields:
Field | Description |
|---|---|
<command result> | Result fields specific to the command that ran. |
ok | A number that indicates if the command succeeded ( 1)
or failed (0). |
operationTime | 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,
For operations associated with causally consistent sessions, the MongoDB drivers use the logical time
to automatically set the Read Operations and |
$clusterTime | 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:
|