Shard a Global Collection for Global Writes in Data Explorer¶
- Global writes are only supported on global clusters, which
require a cluster tier of
- This document assumes prior knowledge of sharding semantics. Review the Sharding documentation before continuing with this tutorial.
In sharded clusters, you can create zones of sharded data based on the shard key. Your zones can segment data based on geographic area. For a complete tutorial on sharding based on geographic area, see Segmenting Data by Location.
The Atlas Data Explorer only supports sharding Global Write
collections inside of a global cluster. To shard non-Global-Write
collections, you must use the
mongo shell or application
code. To learn more, see Deploy a Sharded Cluster.
Review the restrictions and compatibility requirements for Sharding Collections for Global Writes before beginning this procedure.
You can configure Online Archive to move infrequently accessed data from your Atlas cluster to a MongoDB-managed read-only Data Lake instead of sharding your collection or upgrading your cluster tier. To learn more about Online Archive, see Archive Cluster Data.
After selecting a shard key via the Data Explorer, Atlas attempts to shard the target collection. During this period, make sure that no user manually shards the collection. If Atlas detects that the target collection was sharded with a different key than that selected via the Data Explorer, Atlas stops the procedure and displays a warning for that collection in the Data Explorer. You can Click Unmanage Collection to clear the warning. This removes the collection from Atlas management while leaving the underlying collection and the manually chosen shard key intact.
Update Shard Key Value¶
Starting in MongoDB 4.2, you can update a document’s shard key value
unless the shard key field is the immutable
_id field. To learn
more, see Change a Document’s Shard Key Value.
In MongoDB 4.0 and earlier, you cannot update the value of a shard key field in an existing document in a Global Writes-enabled collection.
To shard a collection in a Global Cluster:
Click Clusters in the left navigation pane.¶
Click the Collections button below the cluster that contains the collection that you want to shard.¶
Click the collection that you want to shard.¶
Click the Global Writes tab.¶
Enter the second field of the compound shard key in Second shard key field.¶
Click Shard Collection.¶
Atlas displays the compound shard key near the top of the Global Writes tab after configuring the collection.