replSetGetConfig.txt

================
replSetGetConfig
================

.. versionadded:: 3.0.0

.. default-domain:: mongodb

.. contents:: On this page
   :local:
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   :depth: 1
   :class: singlecol

Definition
----------

.. dbcommand:: replSetGetConfig

   Returns a document that describes the current configuration of the
   :term:`replica set`. To invoke the command directly, use the
   following operation:

   .. code-block:: javascript

      db.runCommand( { replSetGetConfig: 1 } );

   In the :binary:`~bin.mongo` shell, you can access the data provided by
   :dbcommand:`replSetGetConfig` using the :method:`rs.conf()` method,
   as in the following:

   .. code-block:: javascript

      rs.conf();

.. _replSetGetConfig-example:

Output Example
--------------

.. include:: /includes/replica-set-conf-document-output.rst

.. _replSetGetConfig-output:

Replica Set Configuration Fields
--------------------------------

.. data:: replSetGetConfig._id

   *Type*: string

   The name of the replica set. Once set, you cannot change the
   name of a replica set.

   :data:`~replSetGetConfig._id` *must* be identical to the
   :setting:`replication.replSetName` or the value of `--replSet`
   specified to :binary:`~bin.mongod` on the command line.

   .. see::
      :setting:`~replication.replSetName` or :option:`--replSet <mongod --replSet>`
      for information on setting the replica set name.

.. data:: replSetGetConfig.version

   An incrementing number used to distinguish revisions of the replica
   set configuration object from previous iterations of the
   configuration.

``members``
~~~~~~~~~~~

.. data:: replSetGetConfig.members

   *Type*: array

   An array of member configuration documents, one for each member
   of the replica set. The :data:`~replSetGetConfig.members` array
   is a zero-indexed array.

   Each member-specific configuration document can contain the following
   fields:

   .. data:: replSetGetConfig.members[n]._id

      *Type*: integer

      A numeric identifier of every member in the replica set. Once
      set, you cannot change the
      :data:`~replSetGetConfig.members[n]._id` of a member.

      .. note::

         .. include:: /includes/fact-rs-conf-array-index.rst

   .. data:: replSetGetConfig.members[n].host

      *Type*: string

      The hostname and, if specified, the port number, of the set
      member.

      The hostname name must be resolvable for every host in the
      replica set.

      .. warning::

         :data:`~replSetGetConfig.members[n].host` cannot hold a
         value that resolves to ``localhost`` or the local interface
         unless *all* members of the set are on hosts that resolve to
         ``localhost``.

   .. data:: replSetGetConfig.members[n].arbiterOnly

      *Optional*.

      *Type*: boolean

      *Default*: false

      A boolean that identifies an arbiter. A value of ``true``
      indicates that the member is an arbiter.

      When using the :method:`rs.addArb()` method to add an arbiter,
      the method automatically sets
      :data:`~replSetGetConfig.members[n].arbiterOnly` to ``true``
      for the added member.

   .. data:: replSetGetConfig.members[n].buildIndexes

      *Optional*.

      *Type*: boolean

      *Default*: true

      A boolean that indicates whether the :binary:`~bin.mongod` builds
      :term:`indexes <index>` on this member. You can only set this
      value when adding a member to a replica set. You cannot change
      :data:`~replSetGetConfig.members[n].buildIndexes` field after
      the member has been added to the set. To add a member, see
      :method:`rs.add()` and :method:`rs.reconfig()`.

      Do not set to ``false`` for :binary:`~bin.mongod` instances that receive
      queries from clients.

      Setting ``buildIndexes`` to ``false`` may be useful if **all**
      the following conditions are true:

      - you are only using this instance to perform backups using
        :binary:`~bin.mongodump`, *and*

      - this member will receive no queries, *and*

      - index creation and maintenance overburdens the host
        system.

      Even if set to ``false``, secondaries *will* build indexes on the
      ``_id`` field in order to facilitate operations required for
      replication.

      .. warning::

         If you set
         :data:`~replSetGetConfig.members[n].buildIndexes` to
         ``false``, you must also set
         :data:`~replSetGetConfig.members[n].priority` to ``0``. If
         :data:`~replSetGetConfig.members[n].priority` is not
         ``0``, MongoDB will return an error when attempting to add a
         member with
         :data:`~replSetGetConfig.members[n].buildIndexes` equal to
         ``false``.

         To ensure the member receives no queries, you should make all
         instances that do not build indexes hidden.

         Other secondaries cannot replicate from a member where
         :data:`~replSetGetConfig.members[n].buildIndexes` is
         false.

   .. data:: replSetGetConfig.members[n].hidden

      *Optional*.

      *Type*: boolean

      *Default*: false

      When this value is ``true``, the replica set hides this instance
      and does not include the member in the output of
      :method:`db.isMaster()` or :dbcommand:`isMaster`. This prevents
      read operations (i.e. queries) from ever reaching this host by
      way of secondary :term:`read preference`.

      .. seealso::
         :ref:`Hidden Replica Set Members <replica-set-hidden-members>`

   .. data:: replSetGetConfig.members[n].priority

      *Optional*.

      *Type*: Number, between 0 and 1000.

      *Default*: 1.0

      A number that indicates the relative eligibility of a member to
      become a :term:`primary`.

      Specify higher values to make a member *more* eligible to become
      :term:`primary`, and lower values to make the member *less*
      eligible. Priorities are only used in comparison to each other.
      Members of the set will veto election requests from members when
      another eligible member has a higher priority value. Changing the
      balance of priority in a replica set will trigger an election.

      A :data:`~replSetGetConfig.members[n].priority` of ``0``
      makes it impossible for a member to become primary.

      .. seealso::
         :ref:`Replica Set Elections <replica-set-elections>`.

   .. data:: replSetGetConfig.members[n].tags

      *Optional*.

      *Type*: document

      *Default*: none

      .. include:: /includes/fact-tag-set-field.rst

      Use :data:`~replSetGetConfig.replicaset.members[n].tags` to
      configure write concerns in conjunction with
      :data:`~replSetGetConfig.settings.getLastErrorModes` and
      :data:`~replSetGetConfig.settings.getLastErrorDefaults`.

      .. include:: /includes/fact-tag-sets-must-be-strings.rst

      For more information on configuring tag sets for read preference
      and write concern, see
      :doc:`/tutorial/configure-replica-set-tag-sets`.

   .. data:: replSetGetConfig.members[n].slaveDelay

      *Optional*.

      *Type*: integer

      *Default*: 0

      The number of seconds "behind" the primary that this
      replica set member should "lag".

      Use this option to create :ref:`delayed members
      <replica-set-delayed-members>`. Delayed members maintain a copy
      of the data that reflects the state of the data at some time in
      the past.

      .. seealso::
         :doc:`/core/replica-set-delayed-member`

   .. data:: replSetGetConfig.members[n].votes

      *Optional*.

      *Type*: integer

      *Default*: 1

      The number of votes a server will cast in a :ref:`replica set
      election <replica-set-elections>`. The number of votes each
      member has is either ``1`` or ``0``, and :ref:`arbiters
      <replica-set-arbiters>` always have exactly ``1`` vote.

      A replica set can have up to :limit:`50 members
      <Number of Members of a Replica Set>` but only 7 voting members.
      If you need more than 7 members in one replica set, set
      :data:`~replSetGetConfig.members[n].votes` to ``0`` for the
      additional non-voting members.

      .. include:: /includes/members-used-to-allow-multiple-votes.rst

``settings``
~~~~~~~~~~~~

.. data:: replSetGetConfig.settings

   *Optional*.

   *Type*: document

   A document that contains configuration options that apply to the
   whole replica set.

   The :data:`~replSetGetConfig.settings` document contain the
   following fields:

   .. data:: replSetGetConfig.settings.chainingAllowed

      *Optional*.

      *Type*: boolean

      *Default*: true

      When :data:`~replSetGetConfig.settings.chainingAllowed` is
      ``true``, the replica set allows :term:`secondary` members to
      replicate from other secondary members. When
      :data:`~replSetGetConfig.settings.chainingAllowed` is
      ``false``, secondaries can replicate only from the :term:`primary`.

      .. seealso:: :doc:`/tutorial/manage-chained-replication`

   .. data:: replSetGetConfig.settings.getLastErrorDefaults

      *Optional*.

      *Type*: document

      A document that specifies the :doc:`write concern
      </core/replica-set-write-concern>` for the replica set. The
      replica set will use this write concern only when :ref:`write
      operations <write-methods-incompatibility>` or
      :dbcommand:`getLastError` specify no other write concern.

      If :data:`~replSetGetConfig.settings.getLastErrorDefaults` is
      not set, the default write concern for the replica set only
      requires confirmation from the primary.

   .. data:: replSetGetConfig.settings.getLastErrorModes

      *Optional*.

      *Type*: document

      A document used to define an extended :term:`write concern`
      through the use of :data:`~replSetGetConfig.members[n].tags`.
      The extended :term:`write concern` can provide :term:`data-center
      awareness`.

      For example, the following document defines an extended write
      concern named ``eastCoast`` and associates with a write to a
      member that has the ``east`` tag.

      .. code-block:: none

         { getLastErrorModes: { eastCoast: { "east": 1 } } }

      Write operations to the replica set can use the extended write
      concern, e.g. ``{ w: "eastCoast" }``.

      See :doc:`/tutorial/configure-replica-set-tag-sets` for more
      information and example.

   .. data:: replSetGetConfig.settings.heartbeatTimeoutSecs

      *Optional*.

      *Type*: int

      *Default*: 10

      Number of seconds that the replica set members wait for a
      successful heartbeat from each other. If a member does not
      respond in time, other members mark the delinquent member as
      inaccessible.

.. seealso:: :method:`rs.conf()`, :method:`rs.reconfig()`