Keep these considerations in mind when working with External Change Data Capture.
- Each polling request counts toward your Salesforce org’s OData callout rate allocation.
- OData doesn’t differentiate between created and updated change events. Both events are published with update change type.
- When you enable change tracking, a $top=0 query for zero rows is sent to the external data source to tell it to track changes, and a delta link is returned.
- If an error occurs, Salesforce stops sending polling requests. You can check for an error status by querying the BackgroundOperation object or viewing the latest error on the object’s setup page.
- If you create an Apex trigger to respond to change events, these requirements and behaviors apply.
- Create the Apex trigger with development tools, such as the Developer Console or Metadata API or Salesforce UI. You can’t create the trigger from the Salesforce UI.
- Because the Apex trigger runs after an event occurs, only the after-insert trigger event is supported.
- The trigger passes the associated change event, not the object that caused the change.
- Changed records can be committed in the same transaction that started the trigger. However, keep in mind that this transaction is separate from the transaction that created the original event.