DOCSP-15308 reduce oplog entry size

source/reference/parameters.txt

@@ -2098,6 +2098,61 @@ Replication and Consistency
 
       mongod --setParameter maxSessions=1000
 
+.. parameter:: storeFindAndModifyImagesInSideCollection
+
+   .. versionadded:: 5.1
+
+   |both|
+
+   *Type*: boolean
+
+   *Default*: true
+
+   Determines whether the temporary documents required for
+   :ref:`retryable <retryable-writes>` :dbcommand:`findAndModify`
+   commands are stored in the *side* collection
+   (``config.image_collection``).
+
+   If :parameter:`storeFindAndModifyImagesInSideCollection` is:
+
+   - ``true``, the temporary documents are stored in the side
+     collection.
+
+   - ``false``, the temporary documents are stored in the :ref:`replica
+     set oplog <replica-set-oplog>`.
+
+   Keep :parameter:`storeFindAndModifyImagesInSideCollection` set to
+   ``true`` if you:
+
+   - Have a large :ref:`retryable <retryable-writes>`
+     :dbcommand:`findAndModify` workload.
+
+   - Require more temporary document space for :ref:`retryable
+     <retryable-writes>` :dbcommand:`findAndModify` commands than is
+     available in the :ref:`replica set oplog
+     <replica-set-oplog>`.
+
+   .. note::
+
+      :term:`Secondaries <secondary>` may experience increased CPU
+      usage when :parameter:`storeFindAndModifyImagesInSideCollection`
+      is ``true``.
+
+   For example, to set
+   :parameter:`storeFindAndModifyImagesInSideCollection` to ``false``
+   during startup:
+
+   .. code-block:: bash
+
+      mongod --setParameter storeFindAndModifyImagesInSideCollection=false
+
+   During runtime, you can also set the parameter with the
+   :dbcommand:`setParameter` command:
+
+   .. code-block:: javascript
+
+      db.adminCommand( { setParameter: 1, storeFindAndModifyImagesInSideCollection: false } )
+
 .. parameter:: TransactionRecordMinimumLifetimeMinutes
 
    .. versionadded:: 3.6

source/release-notes/5.1.txt

@@ -28,4 +28,18 @@ If the new parameter
 
 - If the new query execution engine is used, new fields are included in
   the :ref:`query explain plan output
-  <explain-results-enhanced-execution>`.
+  <explain-results-enhanced-execution>`.
+
+.. _5.1-rel-notes-repl-sets:
+
+Replica Sets
+------------
+
+``storeFindAndModifyImagesInSideCollection`` Parameter
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Starting in MongoDB 5.1, the
+:parameter:`storeFindAndModifyImagesInSideCollection` parameter
+determines whether the temporary documents required for :ref:`retryable
+<retryable-writes>` :dbcommand:`findAndModify` commands are stored in
+the *side* collection (``config.image_collection``).