DOCS-15960 Add duration of how long an oplog slot is kept open (#4153)

* DOCSP-15960 Add duration of how long an oplog slot is kept open

* DOCS-15960 updates for CR feedback

* DOCSP-15960 include filename correction

* Update source/tutorial/troubleshoot-replica-sets.txt

Co-authored-by: Ashley Brown <[email protected]>

* DOCS-15960 moved example to includes file

---------

Co-authored-by: Ashley Brown <[email protected]>

Author: kanchana-mongodb

source/includes/fact-totalOplogSlotDurationMicros.rst

@@ -0,0 +1,5 @@
+Starting in MongoDB 7.0, the ``totalOplogSlotDurationMicros`` in the
+slow query log message shows the time between a write operation getting
+a commit timestamp to commit the storage engine writes and actually
+committing. ``mongod`` supports parallel writes. However, it commits
+write operations with commit timestamps in any order. 

source/includes/fact-totalOplogSlotDurationMicrosExample.rst

@@ -0,0 +1,10 @@
+Consider the following writes with commit timestamps:
+
+- writeA with Timestamp1
+- writeB with Timestamp2
+- writeC with Timestamp3
+
+Suppose writeB commits first at Timestamp2. Replication is paused
+until writeA commits because writeA's oplog entry with Timestamp1 is
+required for replication to copy the oplog to secondary replica set
+members. 

source/reference/log-messages.txt

@@ -1027,6 +1027,12 @@ profiler <profiler>` entries include a ``cpuNanos`` field that specifies the
 total CPU time spent by a query operation in nanoseconds. The ``cpuNanos`` field 
 is only available on Linux systems.
 
+.. include:: /includes/fact-totalOplogSlotDurationMicros.rst 
+
+.. example:: 
+
+   .. include:: /includes/fact-totalOplogSlotDurationMicrosExample.rst
+
 For a :ref:`pretty-printed <log-message-pretty-printing>` example of a
 slow operation log entry, see :ref:`log-message-json-examples`.
 

source/release-notes/7.0.txt

@@ -154,6 +154,13 @@ migrations:
 - :serverstatus:`shardingStatistics.countDocsClonedOnCatchUpOnRecipient`
 - :serverstatus:`shardingStatistics.countBytesClonedOnCatchUpOnRecipient`
 
+New Slow Query Log Message
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. include:: /includes/fact-totalOplogSlotDurationMicros.rst 
+
+To learn more, see :ref:`log-message-slow-ops`.
+
 New Parameters
 ~~~~~~~~~~~~~~
 

source/tutorial/troubleshoot-replica-sets.txt

@@ -70,6 +70,12 @@ To check the current length of replication lag:
      The :method:`rs.status()` method is a wrapper around the
      :dbcommand:`replSetGetStatus` database command.
 
+  .. include:: /includes/fact-totalOplogSlotDurationMicros.rst
+
+  .. example::
+  
+     .. include:: /includes/fact-totalOplogSlotDurationMicrosExample.rst
+
 - Monitor the rate of replication by checking for non-zero or increasing
   oplog time values in the :guilabel:`Replication Lag` graph available in 
   `Cloud Manager <https://docs.cloudmanager.mongodb.com/reference/alerts/replication-lag/>`_