Change Data Capture Developer Guide

Change Data Capture
Keep Your External Data Current with Change Data Capture
Change Event Message Structure
Merged Change Events
Other Types of Change Events: Gap and Overflow Events
Subscribe to Change Events
Change Event Storage and Delivery
Subscription Channels
Compose Streams of Change Data Capture Notifications with Custom Channels
Example Diagrams for Channels and Channel Members
Transaction-Based Replication Steps
Subscribe with Pub/Sub API
Get Compound Fields in Change Events
Enrich Change Events with Extra Fields
Filter Your Event Streams
Subscribe with Apex Triggers
Monitor Change Event Publishing and Delivery Usage
Security Considerations
Change Event Considerations
Standard Object Notes
Change Events for Fields
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Note: This release is in preview. Features described here don’t become generally available until the latest general availability date that Salesforce announces for this release. Before then, and where features are noted as beta, pilot, or developer preview, we can’t guarantee general availability within any particular time frame or at all. Make your purchase decisions only on the basis of generally available products and features.

Subscription Channels

A subscription channel is a stream of change events that correspond to one or more entities. You can subscribe to a channel to receive change event notifications for record create, update, delete, and undelete operations. Change Data Capture provides predefined standard channels and you can create your own custom channels. Use the subscription channel that corresponds to the change events you want to receive. The channel name is case-sensitive.

You can subscribe to channels by supplying the channel endpoint. For example, to subscribe to events for all selected entities, subscribe to /data/ChangeEvents. Apex triggers can't subscribe to channels but can subscribe to a single event only. For example, you can create an Apex trigger on AccountChangeEvent to subscribe to only Account change events.

Standard Channels

The ChangeEvents standard channel contains change events from one or more selected entities in a single stream that you can subscribe to. If you expect change events from more than one entity, use the ChangeEvents standard channel. To receive change events on the ChangeEvents channel, select the entities for Change Data Capture. For more information, see Select Objects for Change Notifications in the User Interface and Select Objects for Change Notifications with Metadata API and Tooling API. Then subscribe to the appropriate channel.

If you expect change events for only a single entity, use single-entity channels. With single-entity channels, you can subscribe to change events from only one custom object or standard object. Select the entity for notifications on the Change Data Capture page in Setup or in a custom channel.

Standard Channel for All Selected Entities

1/data/ChangeEvents

Single-Entity Channel for a Standard Object

1/data/<Standard_Object_Name>ChangeEvent

For example, the channel to subscribe to change events for Account records is:

1/data/AccountChangeEvent

Single-Entity Channel for a Custom Object

1/data/<Custom_Object_Name>__ChangeEvent

For example, the channel to subscribe to change events for Employee__c custom object records is:

1/data/Employee__ChangeEvent

Custom Channels

Create a custom channel if you have multiple subscribers and each subscriber receives change events from a different set of entities. Also, use a custom channel with event enrichment to isolate sending enriched fields in change events on a specific channel. Custom channels group and isolate change events for each subscriber so subscribers receive only the types of events they need. Entities are automatically selected for change event notifications when you create a custom channel that includes them. A custom channel has the following format.

1/data/YourChannelName__chn

For example, if your channel name is SalesEvents, the subscription channel is:

1/data/SalesEvents__chn