---
title: "Azure Cosmos DB Change Feed: Architecture Patterns and Event Processing"  
description: "Azure Cosmos DB Change Feed: Architecture Patterns and Event Processing"  
author: "Ravi Vishwakarma"  
published: 2026-09-17  
updated: 2026-09-17  
canonical: https://www.mindstick.com/forum/162179/azure-cosmos-db-change-feed-architecture-patterns-and-event-processing  
category: "Event Driven Architecture"  
tags: ["Cosmos DB Change Feed", "Azure Functions", "Event Driven", "Change Feed Processor", "Stream Processing"]  
reading_time: 2 minutes  

---

# Azure Cosmos DB Change Feed: Architecture Patterns and Event Processing

The Azure Cosmos DB **Change Feed** acts as a persistent transaction log that records document insertions and updates in sorted order per logical partition. It provides an efficient mechanism for triggering asynchronous microservices and maintaining search indexes.

## Change Feed Processor vs. Azure Functions Trigger

Developers usually choose between writing custom C# services with the Change Feed Processor library or using the managed Azure Functions Cosmos DB trigger. Azure Functions handles checkpointing, scaling, and partition management automatically behind the scenes.

## Implementing an Azure Function Trigger

Below is a production-ready C# Azure Function consuming document updates directly from Cosmos DB:

```cs
public static class DocumentProcessorFunction
{
    [FunctionName("ProcessContainerChanges")]
    public static async Task Run(
        [CosmosDBTrigger(
            databaseName: "InventoryDb",
            containerName: "Products",
            Connection = "CosmosDBConnectionString",
            LeaseContainerName = "leases",
            CreateLeaseContainerIfNotExists = true)] IReadOnlyList<MyDocument> documents,
        ILogger log)
    {
        // Check if any documents were updated or inserted in this batch
        if (documents != null && documents.Count > 0)
        {
            log.LogInformation($"Processing batch of {documents.Count} modified documents.");

            foreach (var doc in documents)
            {
                // Process individual item change, e.g., publish to Event Grid
                await ProcessItemChangeAsync(doc);
            }
        }
    }
}
```

A dedicated **[lease container](https://www.mindstick.com/forum/34540/ai)** tracks progress across partition leases, enabling multiple function instances to scale horizontally without duplicate processing.


---

Original Source: https://www.mindstick.com/forum/162179/azure-cosmos-db-change-feed-architecture-patterns-and-event-processing

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