DOCSP-30176-resharding-update (#4198)

jason-price-mongodb · jason-price-mongodb · web-flow · commit 0a167417bfa9 · 2023-08-10T17:32:51.000-07:00
* DOCSP-30176-resharding-update * DOCSP-30176-resharding-update * DOCSP-30176-resharding-update * DOCSP-30176-resharding-update * DOCSP-30176-resharding-update * DOCSP-30176-resharding-update * DOCSP-30176-resharding-update * DOCSP-30176-resharding-update * DOCSP-30176-resharding-update * DOCSP-30176-resharding-update * DOCSP-30176-resharding-update * DOCSP-30176-resharding-update * DOCSP-30176-resharding-update * DOCSP-30176-resharding-update * DOCSP-30176-resharding-update * DOCSP-30176-resharding-update * DOCSP-30176-resharding-update * DOCSP-30176-resharding-update * DOCSP-30176-resharding-update * DOCSP-30176-resharding-update * DOCSP-30176-resharding-update * DOCSP-30176-resharding-update --------- Co-authored-by: jason-price-mongodb <jshfjghsdfgjsdjh@aolsdjfhkjsdhfkjsdf.com>
diff --git a/source/core/sharding-reshard-a-collection.txt b/source/core/sharding-reshard-a-collection.txt
@@ -180,6 +180,8 @@ Limitations
 Resharding Process
 ------------------
 
+.. include:: /includes/reshard-collection-introduction.rst
+
 .. include:: /includes/steps/reshard-a-collection.rst
 
 Behavior
diff --git a/source/includes/remainingOperationTimeEstimatedSecs-details.rst b/source/includes/remainingOperationTimeEstimatedSecs-details.rst
@@ -0,0 +1,27 @@
+``remainingOperationTimeEstimatedSecs``: estimated time remaining in
+seconds for the current :ref:`resharding operation
+<sharding-resharding>`. It is returned as ``-1`` when a new resharding
+operation starts.
+
+Starting in:
+
+- MongoDB 5.0, but before MongoDB 6.1,
+  ``remainingOperationTimeEstimatedSecs`` is only available on a
+  :ref:`recipient shard <resharding-process-details>` during a
+  resharding operation.
+- MongoDB 6.1, ``remainingOperationTimeEstimatedSecs`` is also available
+  on the coordinator during a resharding operation.
+
+The resharding operation performs these phases in order:
+
+#. The clone phase duplicates the current collection data.
+#. The catch-up phase applies any pending write operations to the
+   resharded collection.
+
+``remainingOperationTimeEstimatedSecs`` is set to a pessimistic time
+estimate:
+
+- The catch-up phase time estimate is set to the clone phase time, which
+  is a relatively long time.
+- In practice, if there are only a few pending write operations, the
+  actual catch-up phase time is relatively short.
diff --git a/source/includes/reshard-collection-introduction.rst b/source/includes/reshard-collection-introduction.rst
@@ -0,0 +1,13 @@
+In a collection resharding operation, a shard can be a:
+
+- **donor**, which currently stores :term:`chunks <chunk>` for the
+  sharded collection.
+- **recipient**, which stores new chunks for the sharded collection
+  based on the :term:`shard keys <shard key>` and :ref:`zones
+  <zone-sharding>`.
+
+A shard can be donor and a recipient at the same time. The set of donor
+shards is identical to the recipient shards, unless you use zones.
+
+The config server primary is always the resharding coordinator and
+starts each phase of the resharding operation.
diff --git a/source/includes/steps-reshard-a-collection.yaml b/source/includes/steps-reshard-a-collection.yaml
@@ -16,6 +16,7 @@ content: |
 
    MongoDB sets the max number of seconds to block writes to two seconds
    and begins the resharding operation.
+
 ---
 title: Monitor the resharding operation.
 level: 4
@@ -46,8 +47,7 @@ content: |
 
    - ``totalOperationTimeElapsedSecs``: elapsed operation time in
      seconds
-   - ``remainingOperationTimeEstimatedSecs``: estimate of the remaining
-     time to complete the resharding operation
+   - .. include:: /includes/remainingOperationTimeEstimatedSecs-details.rst
 
    .. code-block:: javascript
 
diff --git a/source/reference/command/currentOp.txt b/source/reference/command/currentOp.txt
@@ -1113,18 +1113,10 @@ Output Fields
 
 .. data:: currentOp.remainingOperationTimeEstimatedSecs
 
-   The estimated time remaining in seconds for the current
-   :ref:`resharding operation <sharding-resharding>`. The time is set to
-   -1 when a new resharding operation starts.
-
-   Only present on a :ref:`recipient shard <resharding-process-details>`
-   when a resharding operation is taking place.
+   .. include:: /includes/remainingOperationTimeEstimatedSecs-details.rst
 
    .. versionadded:: 5.0
 
-   Starting in MongoDB 6.1, this metric is also available on the
-   coordinator during resharding.
-
 .. data:: currentOp.allShardsLowestRemainingOperationTimeEstimatedSecs
 
    Calculated across all shards, the lowest estimate of the number of
diff --git a/source/reference/command/reshardCollection.txt b/source/reference/command/reshardCollection.txt
@@ -116,27 +116,13 @@ The :binary:`~bin.mongosh` provides a wrapper method
 Resharding Process
 ------------------
 
-During the resharding process, there are two roles a shard may play:
-
-- **Donors** are shards which currently own chunks of the sharded
-  collection.
-- **Recipients** are shards which would own chunks of the sharded
-  collection according to the new shard key and zones.
-
-A shard may play both the role of a donor and a recipient concurrently.
-Unless zones are being used, the set of donor shards is the same as the
-set of recipient shards.
-
-The config server primary is always chosen as the resharding
-coordinator, responsible for initiating each phase of the process.
+.. include:: /includes/reshard-collection-introduction.rst
 
 Initialization Phase
 ~~~~~~~~~~~~~~~~~~~~
 
-During the initialization phase:
-
-- The balancer determines the new data distribution for the sharded
-  collection.
+During the initialization phase, the resharding coordinator determines
+the new data distribution for the sharded collection.
 
 Index Phase
 ~~~~~~~~~~~
diff --git a/source/reference/method/sh.reshardCollection.txt b/source/reference/method/sh.reshardCollection.txt
@@ -131,27 +131,13 @@ The ``options`` argument supports the following options:
 Resharding Process
 ------------------
 
-During the resharding process, there are two roles a shard may play:
-
-- **Donors** are shards which currently own chunks of the sharded
-  collection.
-- **Recipients** are shards which would own chunks of the sharded
-  collection according to the new shard key and zones.
-
-A shard may play both the role of a donor and a recipient concurrently.
-Unless zones are being used, the set of donor shards is the same as the
-set of recipient shards.
-
-The config server primary is always chosen as the resharding
-coordinator, responsible for initiating each phase of the process.
+.. include:: /includes/reshard-collection-introduction.rst
 
 Initialization Phase
 ~~~~~~~~~~~~~~~~~~~~
 
-During the initialization phase:
-
-- The balancer determines the new data distribution for the sharded
-  collection.
+During the initialization phase, the resharding coordinator determines
+the new data distribution for the sharded collection.
 
 Index Phase
 ~~~~~~~~~~~
