DOCS-13613 Log time spent waiting for shards

source/reference/log-messages.txt

@@ -867,6 +867,38 @@ See the :ref:`examples section <log-message-json-examples>` for a
 :ref:`pretty-printed <log-message-pretty-printing>` version of this log
 entry.
 
+.. _log-messages-remoteOpWaitMillis:
+
+Time Waiting for Shards Logged in ``remoteOpWaitMillis`` Field
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. versionadded:: 5.0
+
+Starting in MongoDB 5.0, you can use the ``remoteOpWaitMillis`` log
+field to obtain the wait time (in milliseconds) for results from
+:term:`shards <shard>`.
+
+``remoteOpWaitMillis`` is only logged:
+
+- If you configure :ref:`slow operations logging
+  <log-message-slow-ops>`.
+
+- On the :term:`shard` or :binary:`~bin.mongos` that merges the results.
+
+To determine if a merge operation or a shard issue is causing a slow
+query, compare the ``durationMillis`` and ``remoteOpWaitMillis`` time
+fields in the log. ``durationMillis`` is the total time the query took
+to complete. Specifically:
+
+- If ``durationMillis`` is slightly longer than ``remoteOpWaitMillis``,
+  then most of the time was spent waiting for a shard response. For
+  example, ``durationMillis`` of 17 and ``remoteOpWaitMillis`` of 15.
+
+- If ``durationMillis`` is significantly longer than
+  ``remoteOpWaitMillis``, then most of the time was spent performing the
+  merge. For example, ``durationMillis`` of 100 and
+  ``remoteOpWaitMillis`` of 15.
+
 .. _log-message-parsing:
 
 Parsing Structured Log Messages

source/release-notes/5.0.txt

@@ -648,6 +648,13 @@ Starting in MongoDB 5.0, :ref:`slow operation
 <database-profiling-specify-slowms-threshold>` log messages include a
 ``remote`` field specifying client IP address.
 
+``remoteOpWaitMillis`` Log Field
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Starting in MongoDB 5.0, you can use the :ref:`remoteOpWaitMillis
+<log-messages-remoteOpWaitMillis>` log field to obtain the wait time for
+results from :term:`shards <shard>`.
+
 Define Variables Using the ``let`` Option
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~