DoorDash Paper: Unified Semantic IDs for Ranking and Query Reformulation

_reachsumit · x · 2026-08-24

DoorDash researchers investigate using a single hierarchical Semantic ID (SID) representation to support personalized ranking and query reformulation across multi-merchant e-commerce catalogs. The hierarchy, learned from product-content embeddings, defines product concepts at multiple granularities. For ranking, the system aggregates consumer affinity and product performance over SID prefixes to derive features. For query reformulation, it grounds queries in SID concepts, using the hierarchy for navigation. Controlled ablations show improved offline relevance and stronger online engagement, including better exposure for less-popular products and finer intent preservation compared to expert-defined taxonomies.

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