• Reference >
• mongo Shell Methods >
• Replication Methods >
• rs.add()

rs.add()

Definition

rs.add()

Adds a member to a replica set. To run the method, you must connect to the primary of the replica set.

Parameter	Type	Description
host	string or document	The new member to add to the replica set. If a string, specify the hostname and optionally the port number for the new member. See Pass a Hostname String to rs.add() for an example. If a document, specify a replica set member configuration document as found in the members array. You must specify _id and the host fields in the member configuration document. See Pass a Member Configuration Document to rs.add() for an example. See Replica Set Configuration document for full documentation of all replica set configuration options
arbiterOnly	boolean	Optional. Applies only if the <host> value is a string. If true, the added host is an arbiter.

rs.add() provides a wrapper around some of the functionality of the replSetReconfig database command and the corresponding mongo shell helper rs.reconfig(). See the Replica Set Configuration document for full documentation of all replica set configuration options.

Behavior

rs.add() can, in some cases, force an election for primary which will disconnect the shell. In such cases, the mongo shell displays an error even if the operation succeeds.

Example

Pass a Hostname String to rs.add()

The following operation adds a mongod instance, running on the host mongodb3.example.net and accessible on the default port 27017:

copy

rs.add('mongodb3.example.net:27017')

If mongodb3.example.net is an arbiter, use the following form:

copy

rs.add('mongodb3.example.net:27017', true)

Pass a Member Configuration Document to rs.add()

The following operation adds a mongod instance, running on the host mongodb4.example.net and accessible on the default port 27017, as a priority 0 secondary member:

copy

rs.add( { _id: 4, host: "mongodbd4.example.net:27017", priority: 0 } )

You must specify _id and the host fields in the member configuration document.

The _id value must be unique. Use rs.conf() to see the existing _id values in the replica set configuration document, and set _id to the next unused _id value in the replica set.

See the Replica Set Configuration for the available replica set member configuration settings.

See Replica Set Tutorials for more examples and information.

←   Replication Methods rs.addArb()  →

© MongoDB, Inc 2008-present. MongoDB, Mongo, and the leaf logo are registered trademarks of MongoDB, Inc.