DOCSP-24449 TTL expireAfterSeconds NaN Behavior alert (#1623)

* DOCSP-24449 TTL expireAfterSeconds NaN Behavior alert

* tech feedack

* link to compat notes from upgrade pre-reqs

* internal review feedback

Author: jmd-mongo

source/includes/valid-ttl-config-prereq.rst

@@ -0,0 +1,9 @@
+Ensure TTL Config is Valid
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Ensure that the :ref:`TTL <ttl-collections>` configuration is valid. 
+Before upgrading, remove or correct any TTL indexes that have 
+``expireAfterSeconds`` set to ``NaN``. In MongoDB 5.0 and later, 
+setting ``expireAfterSeconds`` to ``NaN`` has the same effect as 
+setting ``expireAfterSeconds`` to ``0``. For details, see 
+:ref:`<ttl_expireAfterSeconds_behavior>`.

source/release-notes/5.0-compatibility.txt

@@ -136,6 +136,23 @@ Starting in MongoDB 5.0, the
 present on the :ref:`recipient shard <resharding-process-details>`
 when a :ref:`resharding operation <sharding-resharding>` is taking place.
 
+.. _ttl_expireAfterSeconds_behavior:
+
+TTL ``expireAfterSeconds`` Behavior When Set to ``NaN``
+-------------------------------------------------------
+
+Setting :ref:`TTL <ttl-collections>` ``expireAfterSeconds`` to ``NaN`` 
+experiences a behavior change from MongoDB 4.4 to MongoDB 5.0 that 
+affects: 
+
+- direct upgrades
+- initial sync from earlier versions 
+- :binary:`~bin.mongorestore` from earlier versions. 
+
+Performing any of those actions causes an ``expireAfterSeconds`` of 
+``NaN`` to be treated as an ``expireAfterSeconds`` of ``0``. Immediate 
+document expiration may occur as a result.
+
 Shell Changes
 -------------
 

source/release-notes/5.0-upgrade-replica-set.txt

@@ -29,6 +29,8 @@ The following steps outline the procedure to upgrade a
 Prerequisites
 -------------
 
+.. include:: /includes/valid-ttl-config-prereq.rst
+
 All Members Version
 ~~~~~~~~~~~~~~~~~~~
 

source/release-notes/5.0-upgrade-sharded-cluster.txt

@@ -30,6 +30,8 @@ to |newversion|.
 Prerequisites
 -------------
 
+.. include:: /includes/valid-ttl-config-prereq.rst
+
 All Members Version
 ~~~~~~~~~~~~~~~~~~~
 

source/release-notes/5.0-upgrade-standalone.txt

@@ -29,6 +29,8 @@ The following steps outline the procedure to upgrade a standalone
 Prerequisites
 -------------
 
+.. include:: /includes/valid-ttl-config-prereq.rst
+
 Confirm Clean Shutdown
 ~~~~~~~~~~~~~~~~~~~~~~
 

source/release-notes/6.0-compatibility.txt

@@ -169,6 +169,17 @@ MongoDB 6.0 removes the following server parameters:
        :doc:`reconfigure your TLS/SSL connections </tutorial/configure-ssl>`
        before upgrading.
 
+TTL ``expireAfterSeconds`` Behavior When Set to ``NaN``
+-------------------------------------------------------
+
+Setting :ref:`TTL <ttl-collections>` ``expireAfterSeconds`` to ``NaN`` 
+experiences a behavior change from MongoDB 4.4 to MongoDB 6.0 that 
+affects initial sync from MongoDB 4.4 and earlier and 
+:binary:`~bin.mongorestore` from MongoDB 4.4 and earlier. Performing 
+any of those actions causes an ``expireAfterSeconds`` of ``NaN`` to be 
+treated as an ``expireAfterSeconds`` of ``0``. Immediate document 
+expiration may occur as a result.
+
 Replica Sets
 ------------