Mongo.setCausalConsistency.txt

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Mongo.setCausalConsistency()
============================

.. default-domain:: mongodb

.. contents:: On this page
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Definition
----------

.. method:: Mongo.setCausalConsistency(<boolean>)

   Enables or disables :ref:`causal consistency <causal-consistency>`
   on the connection object. Causal consistency is disabled on the
   connection object by default.
   
   .. note::

      The :method:`Mongo` connection object may have causal consistency
      disabled even though sessions may have causal consistency enabled
      or vice versa. See :method:`Mongo.startSession()`.

   To enable causal consistency for the connection object, call the
   method without any argument:

   .. code-block:: javascript
   
      var conn = Mongo("localhost:27017");
      conn.setCausalConsistency();

   The method also can accept a boolean argument:

   - ``true`` to enable causal consistency:

     .. code-block:: javascript

        conn.setCausalConsistency(true);

   - ``false`` to disable causal consistency:

     .. code-block:: javascript

        conn.setCausalConsistency(false);

Compatibility
-------------

This method is available in deployments hosted in the following environments: 

.. include:: /includes/fact-environments-atlas-only.rst

.. include:: /includes/fact-environments-onprem-only.rst

Example
-------

The following :binary:`~bin.mongosh` operation enables causal
consistency on the :method:`Mongo` connection object associated with
:binary:`~bin.mongosh`'s global ``db`` variable:

.. code-block:: javascript

   db.getMongo().setCausalConsistency();

.. seealso::

   - :method:`db.getMongo()`