How Do You Capture Changes?

Concepts: paCdc

This is the CDC question. The interviewer wants to hear that you know exactly two families of solutions - query-based and log-based - and can articulate when each one wins. The trap is defaulting to timestamp CDC without acknowledging its blind spots. Timestamp-Based CDC The simplest CDC approach and the one most candidates reach for first. Every source table has an updated_at column, your pipeline queries WHERE updated_at > last_watermark. This works if and only if every modification to every row reliably updates the timestamp. The moment one code path or one bulk operation skips the timestamp update, your pipeline silently drops changes. The interviewer knows this. They want you to say it unprompted. Here is the killer follow-up: "What about deletes?" Timestamp CDC cannot detect them. If