Other Types of Change Events: Gap and Overflow Events

Other types of change events are provided to handle special situations, such as capturing changes not caught in the Salesforce application servers, or handling high loads of changes.

Gap Events

Salesforce sometimes sends gap events instead of change events to inform subscribers about errors, or if it’s not possible to generate change events. A gap event contains information about the change in the header, such as the change type and record ID. It doesn’t include details about the change, such as record fields.
Overflow Events

To capture changes more efficiently, overflow events are generated for single transactions that exceed a threshold.