Authors ( listed alphabetically ) Ads Feature Engineering Infra team: Ajay Venkatakrishnan, Le Zhang Core ML Infra team: Eric Shang, Pihui Wei ML Data team: Connor Votroubek, Yi He User Understanding team: Camilo Munoz, Simin Li If you work on ranking, retrieval, or recommendation systems, you’ve probably asked for some version of the same thing: “Give me the last N meaningful actions this user took, with the right enrichments, in a format that’s easy to train and serve ML models.” On paper, that sounds simple. In practice, “user sequences” often become one of the most expensive and fragile pa