Audience member asks how to deal with millions of events in a write-heavy system — keep them forever, snapshot, or compact? Pašalić: depends on business. Some shops use Kafka with log compaction (he doesn't recommend Kafka for this). Financial institutions can snapshot at year-end and archive to S3 or disk. Advertising domains can compact per-campaign once reports are delivered, since post-campaign click data becomes irrelevant. Time-travel then works only up to the compaction point. In e-commerce, archive events out of the transactional store rather than discarding them, so reports and benefits are preserved.