Production designs
Design video recommendations
Separate candidate generation from ranking.
Understand the problem
Ingest impressions and interactions with reliable timestamps. Generate candidates from embeddings, subscriptions, and popular items. Rank a bounded set, apply policy filters, and log exposure for evaluation.
Make it concrete
Training on clicks alone ignores unseen items; exposure logs help distinguish no interest from no opportunity.
Trade-offs and pitfalls
Optimize engagement alongside diversity, safety, and long-term user satisfaction.
Check your understanding
Handle new users, new items, stale features, and a ranking outage.
Practice this topic