Understanding Message Ordering

// All events for account 7 are ordered (same partition)
producer.send(new ProducerRecord<>("ledger", "acct-7", entryJson));

kafka-topics.sh --create --topic audit-log --partitions 1 \
  --replication-factor 3 --bootstrap-server localhost:9092

producer.send(new ProducerRecord<>("orders", customerId, orderEvent));

props.put("enable.idempotence", "true");
props.put("max.in.flight.requests.per.connection", 5);

props.put("enable.idempotence", "true"); // ordering preserved on retries

PriorityQueue<ConsumerRecord<String,String>> pq =
    new PriorityQueue<>(Comparator.comparingLong(ConsumerRecord::timestamp));
records.forEach(pq::add);

long seq = sequencer.next();
r.headers().add("seq", Long.toString(seq).getBytes());

TimeWindows.ofSizeAndGrace(Duration.ofMinutes(5), Duration.ofMinutes(1));

public long extract(ConsumerRecord<Object,Object> r, long prev) {
    return ((Event) r.value()).getEventTimeMs();
}

props.put("enable.idempotence", "true");
props.put("retries", Integer.MAX_VALUE);
props.put("max.in.flight.requests.per.connection", 5);