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
Change Event Triggers
Apex Trigger Quick Start
Apex Trigger Example
Test Change Event Triggers
Change Event Trigger Considerations
Obtain Apex Trigger Subscribers
Monitor Change Event Publishing and Delivery Usage
Security Considerations
Change Event Considerations
Standard Object Notes
Change Events for Fields
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Change Event Trigger Considerations

Keep these considerations in mind when working with change events in Apex triggers.
Triggers for Non-Enabled Objects
You can save an Apex trigger for a change event object even if the object isn’t selected for notifications on the Change Data Capture page. When the object isn’t selected, the trigger doesn't fire. To ensure that the trigger fires, select the object for notifications. Any type of change event fires a change event trigger, including gap events and overflow events.
No Formula Field Support
Formula fields aren't supported in Change Data Capture. They’re null in a change event trigger, regardless of whether they were changed. For information on which field values aren’t included, so are null in a trigger, see Change Event Fields.
Null Name Field for Person Accounts
For a person account, the Name compound field in the AccountChangeEvent received in the trigger is null. The FirstName and LastName fields, which are included in the Name field, contain the person account first name and last name values. In contrast, the ContactChangeEvent Name field contains the concatenated values of the salutation, first name, and last name.
Infinite Trigger Loop
If your trigger updates records of the same object as the one that corresponds to the received change event, then the trigger can fire recursively and exceed limits. To avoid infinite trigger recursion, ensure that you limit your updates so they don't occur every time the trigger refires.