adds fact-drop-indexes-5.0.rst to backport this to v5.0 (#3219)

Author: jmd-mongo

source/includes/fact-drop-indexes-5.0.rst

@@ -0,0 +1,5 @@
+Starting in MongoDB 5.0, |drop-index| raises an error if you attempt
+to use it to remove the last remaining shard key compatible index. 
+Passing ``"*"`` to |drop-index| drops all indexes except 
+the ``_id`` index and the last remaining shard key compatible index, 
+if one exists.

source/reference/command/dropIndexes.txt

@@ -12,13 +12,11 @@ dropIndexes
 
 .. dbcommand:: dropIndexes
 
+   .. versionchanged:: 5.0
+   
    The :dbcommand:`dropIndexes` command drops one or more indexes
-   (except the index on the ``_id`` field) from the specified
-   collection.
-
-   .. |method| replace:: :method:`db.collection.dropIndex()` and
-      :method:`db.collection.dropIndexes()` helper methods.
-   .. include:: /includes/fact-dbcommand-tip
+   (except the index on the ``_id`` field and the last remaining shard
+   key index, if one exists) from the specified collection.
 
    The command has the following form:
 
@@ -46,15 +44,17 @@ dropIndexes
 
         - The index or indexes to drop.
 
-          - To drop all but the _id index from the collection,
-            specify ``"*"``.
+          - To drop all indexes except the ``_id`` index and the last 
+            remaining shard key index from the collection if one 
+            exists, specify ``"*"``.
 
           - To drop a single index, specify either the index name,
             the index specification document (unless the index is a
             :doc:`text </core/index-text>` index), or an array of the
             index name. To drop a :doc:`text </core/index-text>` index,
             specify the index names instead of the index specification
-            document.
+            document. If this index is the last remaining shard key 
+            index, ``dropIndexes`` raises an error.
 
           - To drop multiple indexes (Available starting in MongoDB
             4.2), specify an array of the index names.
@@ -77,6 +77,10 @@ dropIndexes
 Behavior
 --------
 
+.. |drop-index| replace:: :dbcommand:`dropIndexes`
+
+.. include:: /includes/fact-drop-indexes-5.0.rst
+
 Kill related queries only
 ~~~~~~~~~~~~~~~~~~~~~~~~~
 

source/reference/method/db.collection.dropIndexes.txt

@@ -22,7 +22,8 @@ Definition
 
 
    Drops the specified index or indexes (except the index on the
-   ``_id`` field) from a collection.
+   ``_id`` field and the last remaining shard key index) from a 
+   collection.
 
    You can use the method to:
 
@@ -110,7 +111,9 @@ Behavior
 Cannot Drop ``Ready`` Indexes During In-Progress Index Builds
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-.. include:: /includes/fact-5.0-dropindexes-inprog.rst
+.. |drop-index| replace:: :dbcommand:`dropIndexes`
+
+.. include:: /includes/fact-drop-indexes-5.0.rst
 
 Kill related queries only
 ~~~~~~~~~~~~~~~~~~~~~~~~~

source/release-notes/5.0-compatibility.txt

@@ -474,7 +474,13 @@ Starting in MongoDB 5.0:
   creation. The ``wildcardProjection`` document that defines the index 
   may contain :ref:`normalized syntax <normalized_wildcard_indexes>` 
   that differs from the original index creation statements.
-  
+
+- Passing ``"*"`` to :dbcommand:`dropIndexes` or 
+  :method:`db.collection.dropIndexes()` drops all indexes **except**
+  for the ``_id`` index and the last remaining shard key index, if one 
+  exists. Attempts to explicitly drop the last remaining shard key index 
+  raise an error.
+
 Starting in MongoDB 5.0.4 (and 4.4.10), the :query:`$mod`
 operator returns an error if the ``divisor`` or ``remainder`` values
 evaluate to certain values. See :ref:`$mod behavior <mod-behavior>`.