[Preview] Change Feed: Adds Full Fidelity support

[ealsur]

Description

This PR enables the APIs to support Change Feed in Full Fidelity mode. Building on top of the Retention API exposed at #2020 and #2109, once a container has been created with Change Feed retention, Change Feed iterators can be created with Full Fidelity.

Full Fidelity Change Feed exposes creates, replaces, delete operations, including metadata.

The PR exposes a new ChangeFeedMode as a required parameter to initiate any Change Feed iterator. This prompts the user to make a conscious choice of the mode they want to use.

Current Change Feed (the one available until now) is called ChangeFeedMode.Incremental, while the new one is called ChangeFeedMode.FullFidelity.

Creating a container with retention

ContainerProperties containerProperties = new ContainerProperties("myContainer", "/pk");
containerProperties.ChangeFeedPolicy.FullFidelityRetention = TimeSpan.FromMinutes(5);

CosmosContainerResponse containerCreateResponse = await database.CreateContainerAsync(containerProperties, 5000);

Starting an incremental Change Feed (normal Change Feed)

FeedIterator feedIterator = container.GetChangeFeedStreamIterator(
        ChangeFeedStartFrom.Now(),
        ChangeFeedMode.Incremental)

or

FeedIterator<MyType> feedIterator = container.GetChangeFeedIterator<MyType>(
        ChangeFeedStartFrom.Now(),
        ChangeFeedMode.Incremental)

Starting a Change Feed with Full Fidelity

FeedIterator feedIterator = container.GetChangeFeedStreamIterator(
        ChangeFeedStartFrom.Now(),
        ChangeFeedMode.FullFidelity)

or

FeedIterator<MyType> feedIterator = container.GetChangeFeedIterator<MyType>(
        ChangeFeedStartFrom.Now(),
        ChangeFeedMode.FullFidelity)

The document payload available during Full Fidelity responses includes the _metadata attribute which contains the context information (like operationType).

Type of change

• New feature (non-breaking change which adds functionality)

[FabianMeiswinkel]

LGTM Matias - thanks!

[FabianMeiswinkel]

LGTM