Azure Cosmos DB Change Feed: Real-Time Data Processing

Cosmos DB Change Feed lets you react to data changes in real-time. It’s perfect for materializing views, triggering workflows, or syncing to other systems.

What is Change Feed?

A persistent, ordered log of changes to your container. Sorted by modification time within each partition.

With Azure Functions

[FunctionName("ProcessChanges")]
public static void Run(
    [CosmosDBTrigger(
        databaseName: "mydb",
        collectionName: "items",
        ConnectionStringSetting = "CosmosDBConnection",
        LeaseCollectionName = "leases")]
    IReadOnlyList<Document> documents,
    ILogger log)
{
    foreach (var doc in documents)
    {
        log.LogInformation($"Document modified: {doc.Id}");
        // Process change...
    }
}

Use Cases

• Real-time analytics aggregation
• Syncing to search indexes (Elasticsearch)
• Event sourcing patterns
• Triggering notifications

References

• Change Feed Documentation