Change Feed

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Category: Integration & Analytics

Summary: Persistent, ordered log of item inserts/updates, consumable by apps and Azure Functions.

Overview

The change feed is a persistent, ordered log of changes (inserts and updates) made to items within an Azure Cosmos DB container, available for consumption by applications, Azure Functions, or other Azure services. It is a foundational building block for scenarios such as event-driven architectures, real-time analytics, denormalization, referential integrity enforcement, aggregation, and data archiving.

Container monitoredContainer =
    database.GetContainer("Orders");

Container leaseContainer =
    database.GetContainer("Leases");

ChangeFeedProcessor processor =
    monitoredContainer
        .GetChangeFeedProcessorBuilder(
            processorName: "orders-processor",
            onChangesDelegate: HandleChangesAsync)
        .WithLeaseContainer(leaseContainer)
        .Build();

More Info & Links

• Microsoft Learn: Change feed in Azure Cosmos DB

DP-420 Style Practice Questions

Q1. What does the Azure Cosmos DB change feed provide?

• A. A persistent, ordered log of insert/update operations on container items
• B. A one-time export of all data in a container
• C. A record of only delete operations
• D. A backup of the entire database account

Q2. Which of these is a common use case for the change feed?

• A. Denormalizing data or enforcing referential integrity via Azure Functions
• B. Defining the container's partition key
• C. Encrypting data at rest
• D. Configuring the consistency level

Answer Key

Answers are listed at the very end so you can attempt the questions first.

• Q1 (Change Feed): A. A persistent, ordered log of insert/update operations on container items — The change feed captures inserts and updates (not deletes, by default) as an ordered, persistent log for downstream consumption.
• Q2 (Change Feed): A. Denormalizing data or enforcing referential integrity via Azure Functions — Change feed + Azure Functions is commonly used for denormalization, referential integrity, aggregation, and archiving.

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DP-420: Designing and Implementing Cloud-Native Applications Using Microsoft Azure Cosmos DB — term detail page