DOCSP-21874 index-support-reverse-replication (#3225)

* DOCSP-21874-index-support-reverse-replication

* DOCSP-21874-index-support-reverse-replication

* DOCSP-21874-index-support-reverse-replication

* DOCSP-21874-index-support-reverse-replication

* DOCSP-21874-index-support-reverse-replication

* DOCSP-21874-index-support-reverse-replication

* DOCSP-21874-index-support-reverse-replication

* DOCSP-21874-index-support-reverse-replication

---------

Co-authored-by: jason-price-mongodb <[email protected]>

Author: jason-price-mongodb

source/reference/command/collMod.txt

@@ -121,6 +121,10 @@ Change Index Properties
 
       * - ``unique``
         - A boolean that determines whether or not the index is unique.
+          
+          .. note::
+
+             Must be set to ``true``. ``false`` is not supported.
 
           When ``unique`` is ``true``, ``collMod`` scans the
           ``keyPattern`` index for duplicates and then converts it to

source/reference/command/validate.txt

@@ -157,6 +157,13 @@ consistent sessions <causal-consistency>`. Starting in MongoDB 4.2, the
 associated with :ref:`causally consistent sessions
 <causal-consistency>`.
 
+Index Key Format
+~~~~~~~~~~~~~~~~
+
+Starting in MongoDB 6.0, the ``validate`` command returns a message if a
+:ref:`unique index <index-type-unique>` has a key format that is
+incompatible. The message indicates an old format is used.
+
 Examples
 --------
 

source/release-notes/6.0-compatibility.txt

@@ -79,6 +79,14 @@ single document.
 
 See :parameter:`indexMaxNumGeneratedKeysPerDocument`.
 
+Index Key Format
+~~~~~~~~~~~~~~~~
+
+Starting in MongoDB 6.0, a change to the :ref:`unique index
+<index-type-unique>` key format was introduced. If you create a unique
+index in MongoDB 6.0, the index won't work with MongoDB versions earlier
+than 5.3.2 or 5.0.7.
+
 Legacy ``mongo`` Shell Removed
 ------------------------------