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DOCS-8540 #2747

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49c2270
Added warning about movePrimary command
joannac- Oct 13, 2016
983535d
Fixed wording for clarity.
joannac- Oct 27, 2016
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13 changes: 13 additions & 0 deletions source/includes/warning-movePrimary.rst
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@@ -0,0 +1,13 @@
.. warning::

If you use the :dbcommand:`movePrimary` command to move un-sharded
collections, you must either restart all :program:`mongos` instances,
or use the :dbcommand:`flushRouterConfig` command on all
:program:`mongos` instances before reading or writing any data to any
unsharded collections that were moved. This action ensures that the
:program:`mongos` is aware of the new shard for these collections.

If you do not update the :program:`mongos` instances' metadata cache
after using :dbcommand:`movePrimary`, the :program:`mongos` may miss data
on reads, and may not write data to the correct shard. To recover, you must
manually intervene.
18 changes: 1 addition & 17 deletions source/reference/command/movePrimary.txt
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Expand Up @@ -47,8 +47,7 @@ movePrimary
Considerations
--------------

Behavior
~~~~~~~~
.. include:: /includes/warning-movePrimary.rst

Avoid accessing an un-sharded collection during migration.
:dbcommand:`movePrimary` does not prevent reading and writing during its
Expand All @@ -62,21 +61,6 @@ conflicting collection name. This may occur if documents are written to an
un-sharded collection while the collection is moved away, and later the original
primary shard is restored.

Use
~~~

If you use the :dbcommand:`movePrimary` command to move un-sharded
collections, you must either restart all :program:`mongos` instances,
or use the :dbcommand:`flushRouterConfig` command on all
:program:`mongos` instances before reading or writing writing any data to the
database that was moved. This action notifies the :program:`mongos` of the new shard
for the database.

If you do not update the :program:`mongos` instances' metadata cache
after using :dbcommand:`movePrimary`, the :program:`mongos` may miss data
on reads, and may not write data to the correct shard. To recover, you must manually
intervene.

Additional Information
----------------------

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6 changes: 6 additions & 0 deletions source/tutorial/remove-shards-from-cluster.txt
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Expand Up @@ -177,6 +177,12 @@ primary shards.)

{ "primary" : "mongodb1", "ok" : 1 }

.. warning::

The :dbcommand:`movePrimary` command has many considerations, please
carefully review the documentation to ensure that these are correctly
handled.

.. _remove-shard-finalize-migration:

Finalize the Migration
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