Kafka विविध delivery guarantees समर्थन करतो — at-most-once, at-least-once, आणि exactly-once — जे निर्धारित करतात की संदेश हरवले जाऊ शकतात किंवा डुप्लिकेट होऊ शकतात. हे समजून घेणे आणि कसे साधायचे हे विश्वसनीय प्रणाली तयार करण्यासाठी महत्त्वाचे आहे.
तीन delivery semantics
AT-MOST-ONCE → messages may be LOST but never duplicated:
→ commit offset BEFORE processing → if processing fails, the message is skipped (lost)
→ for: when occasional loss is acceptable and duplicates are not (rare)
AT-LEAST-ONCE → messages are never lost but may be DUPLICATED:
→ commit offset AFTER processing → if a crash occurs before commit, the message is
reprocessed (duplicate) → requires IDEMPOTENT processing
→ the common default; safe (no loss) but handle duplicates
EXACTLY-ONCE → each message is processed exactly once (no loss, no duplicates):
→ the strongest, but hardest; requires Kafka transactions + idempotent producers
