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- rs.add()
rs.add()¶
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Definition¶
-
rs.
add
(host, arbiterOnly)¶ 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 specifymembers[n]._id
and themembers[n].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. Iftrue
, the added host is an arbiter.rs.add()
provides a wrapper around some of the functionality of thereplSetReconfig
database command and the correspondingmongo
shell helperrs.reconfig()
. See the Replica Set Configuration document for full documentation of all replica set configuration options.
Behavior¶
rs.add()
can, in some cases, trigger an election for primary
which will disconnect the shell (such as adding a new member with
a higher priority than the current primary). In such cases, the mongo
shell may display 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
:
rs.add('mongodb3.example.net:27017')
If mongodb3.example.net
is an arbiter, use the following form:
rs.add('mongodb3.example.net:27017', true)
For the following MongoDB versions, pv1
increases the likelihood
of w:1
rollbacks compared to pv0
for replica sets with arbiters:
- MongoDB 3.4.1
- MongoDB 3.4.0
- MongoDB 3.2.11 or earlier
Pass a Member Configuration Document to rs.add()
¶
Changed in version 3.0.0: Previous versions required an _id
field in the document you
passed to rs.add()
. After 3.0.0 you can omit the
_id
field in this document.
members[n]._id
describes the requirements for specifying _id
.
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:
rs.add( { host: "mongodbd4.example.net:27017", priority: 0 } )
You must specify the
members[n].host
field in the member
configuration document.
See the Replica Set Configuration for the available replica set member configuration settings.
See Replica Set Tutorials for more examples and information.