Taobao's URED recycles high-scored but unexposed candidates: +3.47% discovered categories

_reachsumit · x · 2026-11-06

Alibaba's paper introduces URED (Unexposed Recycling for Efficient Discovery), a training-free recall-stage system that has served Taobao feed recommendation for over six months to tens of millions of DAU.

Key insight: naively boosting under-explored content fails in production because it injects cold, information-poor candidates that rankers systematically over-estimate — no discovery gain, real engagement risk. Items scored highly but never exposed form a pool that is both relevant and reliably predictable, yet industrial pipelines routinely discard this signal.

Approach: URED aggregates these candidates over a 30-day horizon and re-injects them at recall time via a lightweight pipeline (offline storage, distributed aggregation, low-latency serving), adding under 1% latency with a single O(1) lookup per request and no retraining.

Online A/B tests: +3.47% discovered categories, +8.47% content richness, completion video views +2.62%, total views +0.36% (not significant). Ablations show both design pillars are necessary — a one-day window collapses the gains.

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