Change Data Capture Developer Guide

Change Data Capture
Keep Your External Data Current with Change Data Capture
Change Event Message Structure
Subscribe to Change Events
Security Considerations
Change Event Considerations
General Considerations
Change Data Capture Allocations
Standard Object Notes
Change Events for Fields
Other Types of Change Events: Gap and Overflow Events
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General Considerations

Change Event Persistence
Change events are temporarily persisted to and served from an industry-standard distributed system during the retention period of three days. A distributed system doesn’t have the same semantics or guarantees as a transactional database. Change events are queued and buffered, and Salesforce attempts to publish the events asynchronously. In rare cases, the event message might not be persisted in the distributed system during the initial or subsequent attempts. This means that the events aren’t delivered to subscribers, and they aren’t recoverable.
No Change Events Generated for Some Actions
The following actions don’t generate change events for affected records.
  • Any action related to state and country picklists that you perform in Setup on the State and Country/Territory Picklists page.
  • Changing the type of an opportunity stage picklist value.
  • When a custom picklist field is defined on Contact in a person account org, the field is present on Account with the __pc suffix. Replacing or renaming a value of the custom picklist doesn’t generate account change events but only contact change events for the affected records. However, if the custom picklist field is defined on Account, the field is not present on Contact and only account change events are generated, as expected.
No Formula Field Support
Formula fields aren't supported in Change Data Capture. They aren't included in change events that are delivered to CometD clients. Formula fields are included in change events in Apex triggers, but they have a value of null regardless of whether they were changed.
Geolocation Compound Fields
When a geolocation compound field (of type location) is changed in a custom object, all its component fields are published in the change event whether they were changed or not. In contrast, when a geolocation field is changed in a standard object, only the changed field is published. For more information, see Geolocation Compound Field in the SOAP API Developer Guide.