DOCS-13283 Two phase commit use lower write concern

Author: jason-price-mongodb

source/core/transactions.txt

@@ -698,11 +698,12 @@ values, including:
      concern guarantees that operations have from a synchronized
      snapshot of majority-committed data.
 
-
 .. note::
 
    .. include:: /includes/extracts/transactions-sharded-clusters-commit-writeconcern.rst
-   
+
+   .. include:: /includes/return-commit-decision-parameter.rst
+
 General Information
 -------------------
 

source/includes/return-commit-decision-parameter.rst

@@ -0,0 +1,8 @@
+Starting in MongoDB 5.0, the new server parameter
+:parameter:`coordinateCommitReturnImmediatelyAfterPersistingDecision`
+controls when transaction commit decisions are returned to the client.
+In previous versions of MongoDB, the :doc:`shard
+</core/sharded-cluster-shards>` transaction coordinator waited for all
+members to acknowledge a :ref:`multi-document transaction
+<transactions-atomicity>` commit before returning the commit decision to
+the client.

source/reference/command/commitTransaction.txt

@@ -37,21 +37,21 @@ Definition
         writeConcern: <document>,
         autocommit: false,
         comment: <any>
-       }
+      }
 
 Behavior
 --------
 
 Write Concern
 ~~~~~~~~~~~~~
 
-When committing the transaction, the session uses the write concern
-specified at the transaction start. See
-:method:`Session.startTransaction()`.
+When committing the transaction, the session uses the :doc:`write
+concern </reference/write-concern>` specified at the transaction start.
+See :method:`Session.startTransaction()`.
 
-If you commit using :writeconcern:`"w: 1" <\<number\>>` write concern,
-your transaction can be :doc:`rolled back if there is a failover.
-</core/replica-set-rollbacks>`.
+If you commit using the :writeconcern:`"w: 1" <\<number\>>` write
+concern, your transaction can be :doc:`rolled back if there is a
+failover. </core/replica-set-rollbacks>`.
 
 Atomicity
 ~~~~~~~~~

source/reference/parameters.txt

@@ -3622,6 +3622,45 @@ Auditing Parameters
 Transaction Parameters
 ~~~~~~~~~~~~~~~~~~~~~~
 
+.. parameter:: coordinateCommitReturnImmediatelyAfterPersistingDecision
+
+   .. versionadded:: 5.0
+
+   *Type*: boolean
+
+   *Default*: true
+
+   |mongod-only|
+
+   If ``true``, the :doc:`shard </core/sharded-cluster-shards>`
+   transaction coordinator returns a :ref:`multi-document transaction
+   <transactions-atomicity>` commit decision to the client as soon as
+   the commit is made :term:`durable` with the requested transaction
+   :doc:`write concern </reference/write-concern>`. If the client
+   requested a write concern that is less than
+   :writeconcern:`"majority"`, the commit may roll back after the
+   decision is returned to the client.
+
+   If ``false``, the :doc:`shard </core/sharded-cluster-shards>`
+   transaction coordinator waits for all members to acknowledge a
+   :ref:`multi-document transaction <transactions-atomicity>` commit
+   before returning the commit decision to the client.
+
+   The following example sets
+   :parameter:`coordinateCommitReturnImmediatelyAfterPersistingDecision`
+   to ``false``:
+
+   .. code-block:: javascript
+
+      mongod --setParameter coordinateCommitReturnImmediatelyAfterPersistingDecision=false
+
+   During runtime, you can also set the parameter with the
+   :dbcommand:`setParameter` command:
+
+   .. code-block:: sh
+
+      db.adminCommand( { setParameter: 1, coordinateCommitReturnImmediatelyAfterPersistingDecision: false } )
+
 .. parameter:: transactionLifetimeLimitSeconds
 
    .. versionadded:: 4.0

source/release-notes/5.0.txt

@@ -85,6 +85,11 @@ Starting in MongoDB 5.0, :ref:`change-events`
 contain the field ``updateDescription.truncatedArrays`` to record array
 truncations.
 
+``coordinateCommitReturnImmediatelyAfterPersistingDecision`` Parameter
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. include:: /includes/return-commit-decision-parameter.rst
+
 .. _5.0-rel-notes-security:
 
 Security Improvements