IntegrationIntermediatecdcfilteringchangedfields
Filter CDC ChangeEventHeader changedFields in Apex and middleware subscribers
Real World Scenario
Subscriber processes every Account CDC event but only BillingCity changes matter; CPU cost triples processing irrelevant field updates.
Expected Answer
• Parse ChangeEventHeader changedFields array before business logic
• Early return if intersection with watch list empty
• changedFields includes compound address subfields explicitly
• Create events omit changedFields null handle separately
• Delete events process regardless changedFields
• Unit test filter with mock ChangeEvent payload
• Combine with Salesforce CDC field selection at source
Follow-Up Questions & Answers
Click to expand — each follow-up includes a direct, interview-ready answer
Direct answer: Parse ChangeEventHeader changedFields array before business logic Also consider: Early return if intersection with watch list empty In practice: changedFields includes compound address subfields explicitly Balance speed of delivery with maintainability.
Architect Perspective
changedFields filter is cheap subscriber optimization—apply before any external callout.