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Disable balancer while indexes are inconsistent #1766

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4197c9b
Update orderby.txt
Boomtime Jan 30, 2014
ec5f94a
tweak orderby size limit blurb
kay-kim May 8, 2014
78cc4c8
Reordered steps, added detail to step 2
joannac- Jan 28, 2014
173f5c3
reorg restore sharded clusters steps
kay-kim May 8, 2014
13ce981
trivial: swap step 5 and 6 in restore sharded cluster tutorial
kay-kim May 8, 2014
1e461aa
Disable balancer while indexes are inconsistent
achille May 8, 2014
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19 changes: 13 additions & 6 deletions source/reference/operator/meta/orderby.txt
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Expand Up @@ -29,9 +29,16 @@ $orderby
``-1``, as above) to sort in descending order or a positive value
(e.g. ``1``) to sort in ascending order.

Unless you have an index for the specified key pattern, use
:operator:`$orderby` in conjunction with :operator:`$maxScan` and/or
:method:`cursor.limit()` to avoid requiring MongoDB to perform a
large in-memory sort. The :method:`cursor.limit()` increases the
speed and reduces the amount of memory required to return this query
by way of an optimized algorithm.
Behavior
--------

The sort function requires that the entire sort be able to complete
within 32 megabytes. When the sort option consumes more than 32
megabytes, MongoDB will return an error.

To avoid this error, create an index to support the sort operation or
use :operator:`$orderby` in conjunction with :operator:`$maxScan`
and/or :method:`cursor.limit()`. The :method:`cursor.limit()` increases
the speed and reduces the amount of memory required to return this
query by way of an optimized algorithm. The specified limit must result
in a number of documents that fall within the 32 megabyte limit.
10 changes: 9 additions & 1 deletion source/tutorial/build-indexes-on-replica-sets.txt
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Expand Up @@ -51,7 +51,15 @@ Procedure

If you need to build an index in a :term:`sharded cluster`, repeat
the following procedure for each replica set that provides each
:term:`shard`.
:term:`shard`. Also ensure the balancer has been disabled for all
collections on which you'll be creating an new index. This will prevent
an automatic index build as chunks are migrated. The balancer should be
enabled after the indexes have been updated on all shards.
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putting this fact here is pretty awkward, because the tutorial isn't about sharded clusters, and so this fact might be weird for users in a sharded cluster. Perhaps we can put this fact somewhere else and then cross reference it here?


.. code-block:: sh

sh.disableBalancing("dbName.collectionName");


.. _tutorial-index-on-replica-sets-stop-one-member:

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43 changes: 20 additions & 23 deletions source/tutorial/restore-sharded-cluster.txt
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Expand Up @@ -28,25 +28,6 @@ Procedure
#. Stop all :program:`mongos` and :program:`mongod` processes,
including all shards *and* all config servers.

#. If shard hostnames have changed, you must manually update the
``shards`` collection in the :ref:`config-database` to use the new
hostnames. Do the following:

a. Start the three :ref:`config servers <sharding-config-server>` by
issuing commands similar to the following, using values appropriate
to your configuration:

.. code-block:: sh

mongod --configsvr --dbpath /data/configdb --port 27019

#. Restore the :ref:`config-database` on each config server.

#. Start one :program:`mongos` instance.

#. Update the :ref:`config-database` collection named ``shards`` to reflect the
new hostnames.

#. Restore the following:

- Data files for each server in each :term:`shard`. Because replica
Expand All @@ -56,14 +37,30 @@ Procedure
:ref:`backup-restore-snapshot` and :ref:`backup-restore-dump`
sections for details on these procedures.

- Data files for each :ref:`config server <sharding-config-server>`,
if you have not already done so in the previous step.
- Data files for each :ref:`config server <sharding-config-server>`.

#. Restart all the :ref:`config servers <sharding-config-server>`
:program:`mongod` instances by issuing command similar to the
following, using values appropriate
to your configuration:

.. code-block:: sh

mongod --configsvr --dbpath /data/configdb --port 27019

#. If shard hostnames **have changed**:

a. Start one :program:`mongos` instance, using the updated
config string with the new ``configdb`` hostnames and ports.

#. Update the ``shards`` collection in the :ref:`config-database` to
reflect the new hostnames.

#. Restart all the :program:`mongos` instances.
#. Stop the :program:`mongos` instance.

#. Restart all the shard :program:`mongod` instances.

#. Restart all the config servers :program:`mongod` instances.
#. Restart all the :program:`mongos` instances, making sure to use the updated config string.

#. Connect to a :program:`mongos` instance from a :program:`mongo` shell
and use the :method:`db.printShardingStatus()` method to ensure
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