DOCS-15946 Documents buildIndexes option (#120)

* DOCS-15946 Documents buildIndexes option

* Adjusts text

* Fixes per Jason Price

* Fixes per Rohan Sharan

* Forces build

* Adjusts text

* Fixes per Rohan Sharan

* Update source/reference/api/start.txt

Co-authored-by: Rohan Sharan <[email protected]>

* Update source/reference/api/start.txt

Co-authored-by: Rohan Sharan <[email protected]>

* Fixes per Rohan Sharan

* Fixes per Rohan Sharan

* Update source/reference/api/start.txt

Co-authored-by: Rohan Sharan <[email protected]>

* Fixes per Rohan Sharan

* Fixes per Rohan Sharan

* Fixes per Rohan Sharan

---------

Co-authored-by: Rohan Sharan <[email protected]>

Author: kennethdyer

source/reference/api/start.txt

@@ -91,6 +91,38 @@ Request Body Parameters
      - Required
      - Name of the destination cluster.
 
+   * - ``buildIndexes``
+     - boolean
+     - Optional
+     - Configures index builds during sync.
+
+       Supported Options:
+
+       - ``beforeDataCopy`` (the default) causes ``mongosync`` to build indexes
+         on the destination cluster. These include both existing indexes and
+         any indexes created during migration on the source cluster.
+
+       - ``never`` causes ``mongosync`` to skip building unnecessary indexes 
+         during sync.  This can improve migration performance, especially with 
+         index heavy workloads.
+
+         .. warning::
+
+            Do **not** manually build indexes while ``mongosync`` is 
+            performing a migration.  Wait until the migration is fully 
+            committed.
+
+         For more information on the indexes it does build, see 
+         :ref:`c2c-required-indexes`.
+
+       ``/start`` returns an error when ``buildIndexes`` is set to ``never``
+       and ``reversible`` is set to ``true``.
+
+       If you call ``/start`` without specifying the ``buildIndexes`` option,
+       ``mongosync`` builds indexes on the destination cluster.
+
+       .. versionadded:: 1.3.0
+
    * - ``enableUserWriteBlocking``
      - boolean
      - Optional
@@ -136,6 +168,8 @@ Request Body Parameters
        * Sync from a replica set to a sharded cluster
 
        * Sync sharded clusters that have different numbers of shards
+
+       * Reversible sync when ``buildIndexes`` is set to ``never``.
 
        For more information, see the :ref:`reverse <c2c-api-reverse>` endpoint.
 
@@ -144,7 +178,7 @@ Request Body Parameters
    * - ``sharding``
      - document
      - Optional
-     - Configure sync between a replica set and sharded cluster.
+     - Configures sync between a replica set and sharded cluster.
        Sync from a replica set to a sharded cluster requires this
        option.
 
@@ -406,4 +440,22 @@ To check whether it is safe to rename collections, call the
   Renaming the collection from this point on does not block
   its sharding on the destination cluster, even in the event  of a crash.
 
+.. _c2c-required-indexes:
+
+Required Indexes
+~~~~~~~~~~~~~~~~
+
+When you call ``/start`` with the ``buildIndexes`` option set to ``never``,
+``mongosync`` skips building unnecessary indexes.  
+
+Indexes that are always built include:
+
+* ``mongosync`` builds an index on the ``_id`` field of every
+  collection it copies.
+
+* Starting in MongoDB 6.0, ``mongosync`` builds dummy indexes that support 
+  the shard key for each sharded collection, which are removed after commit.
+  When ``buildIndexes`` is set to ``never``, ``mongosync`` retains this
+  index after commit.
 
+  

source/release-notes/1.3.txt

@@ -22,4 +22,13 @@ Capped Collections
 
 Starting in 1.3.0, {+c2c-product-name+} supports :ref:`capped
 collections <manual-capped-collection>`. For more information, see
-:ref:`c2c-capped-collections`.
+:ref:`c2c-capped-collections`.
+
+Disable Index Builds
+--------------------
+
+Starting in 1.3.0, {+c2c-product-name+} supports disabling non-essential
+index builds on the destination cluster.  This can improve migration 
+performance, especially with index heavy workloads.
+
+For more information, see :ref:`c2c-api-start`.