Choose when to distribute data

When it comes to designing and implementing native applications using Microsoft Azure Cosmos DB, one important consideration is deciding when to distribute data. Distributing data effectively can enhance the performance, availability, and scalability of your application. Azure Cosmos DB offers multiple distribution models to meet different application requirements. In this article, we will explore these distribution models and highlight their usage scenarios.

Overview of Azure Cosmos DB

Azure Cosmos DB is a fully managed, globally distributed, and multi-model database service provided by Microsoft Azure. It offers support for NoSQL APIs including Document DB, MongoDB, Cassandra, Graph, and Table API. With Azure Cosmos DB, you can store and access data using the preferred API and distribute it across multiple regions for low-latency global access.

Distribution Models in Azure Cosmos DB

1. Single-region distribution:

In this model, data is stored and replicated within a single region. This approach is suitable for applications with a small user base or where data compliance regulations require data to stay within specific geographic boundaries. The single-region distribution model provides high availability within that region but lacks global scalability.

Here’s an example of how to configure single-region distribution using the .NET SDK:

csharp
DocumentClient client = new DocumentClient(new Uri(endpointUrl), authKey);

Database database = await client.CreateDatabaseAsync(new Database { Id = “MyDatabase” });

DocumentCollection collection = new DocumentCollection { Id = “MyCollection” };
collection.PartitionKey.Paths.Add(“/city”);

await client.CreateDocumentCollectionAsync(database.SelfLink, collection);

2. Multi-region distribution:

This model involves replicating data across multiple regions for improved availability, disaster recovery, and reduced latency. Azure Cosmos DB automatically synchronizes data across these regions in real-time.

To set up multi-region distribution, you can specify the regions in which you want data to be replicated when creating an Azure Cosmos DB account. Azure Cosmos DB uses a conflict-free replicated data type (CRDT) to handle eventual consistency and conflict resolution across regions.

Here’s an example of creating a multi-region distributed database account using Azure CLI:

bash
az cosmosdb create \
–name mycosmosaccount \
–kind GlobalDocumentDB \
–locations “East US”=0 “West US”=1 “North Europe”=2 \
–default-consistency-level Eventual \
–resource-group myresourcegroup

3. Paired region distribution:

With paired region distribution, Azure Cosmos DB automatically pairs regions in close proximity to each other to provide better availability and data durability. Paired regions are ideal for scenarios where you require strong consistency and the ability to fail over in case of regional outages.

By configuring the preferred locations, you can control the read and write regions for your application. Azure Cosmos DB automatically routes requests to the nearest available region or the one specified as the write region.

Here’s an example of specifying the preferred locations using the Azure portal:

1. Go to Azure portal > Azure Cosmos DB account.
2. In the left-hand menu, select “Azure Cosmos DB account” > “Replicate data globally”.
3. In the “Replicate data globally” blade, click on “Add region”.
4. Select the desired region from the list and set it as the preferred location.
5. Repeat steps 3 and 4 for additional preferred locations.
6. Click “Save” to apply the changes.

Conclusion

Choosing the right data distribution model in Azure Cosmos DB is crucial for optimizing your application’s performance and availability. Whether you opt for single-region, multi-region, or paired region distribution depends on your specific requirements, such as target user base, compliance regulations, and desired availability levels. By leveraging Azure Cosmos DB’s flexible distribution options, you can build robust and scalable native applications with ease.