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Shard a Global Collection for Global Writes in Data Explorer

Feature incompatible with Multi-Cloud Clusters

Atlas doesn’t support this feature in multi-cloud clusters at this time.

Note

  • Global writes are only supported on global clusters, which require a cluster tier of M30 or greater.
  • 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.

Required Roles

You must have the Project Owner or Organization Owner role for the cluster’s Atlas project to shard a collection for Global Writes in the Data Explorer.

Considerations

Review the restrictions and compatibility requirements for Sharding Collections for Global Writes before beginning this procedure.

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.

Procedure

To shard a collection in a Global Cluster:

1

Click Clusters in the left navigation pane.

2

Click the Collections button below the cluster that contains the collection that you want to shard.

3

Click the collection that you want to shard.

4

Click the Global Writes tab.

5

Enter the second field of the compound shard key in Second shard key field.

6

Click Shard Collection.

Atlas displays the compound shard key near the top of the Global Writes tab after configuring the collection.