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DOCS-9937 added section about server tracking metadata for multikey covering #2950

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Merged
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Sep 8, 2017
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DOCS-9937 added section about server tracking metadata for multikey covering #2950

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8 changes: 8 additions & 0 deletions source/core/query-optimization.txt
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Expand Up @@ -149,6 +149,14 @@ The ``{ "user.login": 1 }`` index will cover the query below:
.. [#index-embedded-document-fields] To index fields
in embedded documents, use :term:`dot notation`.

Multikey Covering
~~~~~~~~~~~~~~~~~

Starting in 3.6, multikey indexes can cover queries over the non-array fields
if the index tracks which field or fields cause the index to be multikey.
Multikey indexes created in MongoDB 3.4 or later on storage engines other
than MMAPv1 track this data.

Performance
~~~~~~~~~~~

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2 changes: 1 addition & 1 deletion source/includes/fact-geospatial-index-covered-query.rst
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@@ -1,2 +1,2 @@
A :ref:`geospatial indexes <index-feature-geospatial>` cannot
:ref:`Geospatial indexes <index-feature-geospatial>` cannot
:ref:`cover a query <covered-queries>`.
4 changes: 2 additions & 2 deletions source/includes/fact-multikey-index-covered-query.rst
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@@ -1,2 +1,2 @@
:ref:`Multikey indexes <index-type-multikey>` cannot :ref:`cover a
query <covered-queries>`.
:ref:`Multikey indexes <index-type-multikey>` cannot cover queries
over array field(s).
4 changes: 3 additions & 1 deletion source/release-notes/3.6.txt
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Expand Up @@ -177,9 +177,11 @@ MongoDB 3.6 includes the following enhancements:

.. note:: FTDC is enabled by default.

- Multikey indexes can cover queries over non-array keys if the index
tracks which fields make it multikey.

- If authentication is turned on, you can only issue a :dbcommand:`getMore`
against cursors you created
against cursors you created.

Changes Affecting Compatibility
-------------------------------
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