db.collection.checkMetadataConsistency.txt

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db.collection.checkMetadataConsistency()
========================================

.. default-domain:: mongodb

.. contents:: On this page
   :local:
   :backlinks: none
   :depth: 1
   :class: singlecol

Definition
----------

.. method:: db.collection.checkMetadataConsistency(options)

   Performs a series of consistency checks on sharding metadata 
   for the collection. The method returns a cursor with either all or a
   batch of the inconsistency results found.

   .. |dbcommand| replace:: :dbcommand:`checkMetadataConsistency` command
   .. include:: /includes/fact-mongosh-shell-method-alt.rst

   Run this method after major maintenance operations, such as upgrades and
   downgrades, to check the state of the catalog.

   .. include:: /includes/inconsistency-type/index-note

   For more information on the inconsistencies this method checks for,
   see :ref:`inconsistency-types`.

   :returns: This method returns a cursor with a ``documents`` array, 
      which contains a document for each inconsistency found in 
      the sharding metadata.


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

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

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

.. include:: /includes/fact-environments-atlas-support-no-free.rst

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

.. include:: /includes/method/checkMetadataConsistency-execute-mongos.rst


Syntax
-------

The :method:`db.collection.checkMetadataConsistency` method has the following syntax:

.. code-block:: javascript

   db.collection.checkMetadataConsistency( { <options> } )

The ``options`` document can take the following fields and values:

.. include:: /includes/inconsistency-type/checkMetadataConsistency-options.rst


Example
-------

.. io-code-block::

   .. input::
      :language: javascript

      db.authors.checkMetadataConsistency()

   .. output::
      :language: json

      {
         cursorHasMore: false,
         documents: [
            {
               type: "MisplacedCollection",
               description: "Unsharded collection found on shard different from database primary shard",
               details: {
                  namespace: "test.authors",
                  shard: "shard02",
                  localUUID: new UUID("1ad56770-61e2-48e9-83c6-8ecefe73cfc4")
               }
            }
         ],
      }