System designMediumsd-g103

Subject Vector databaseLevel Mid–Senior~40 minCommon in Databases & SQL interviewsIndustries Technology, Software development

Question

Design search for a real-estate listings site where users issue natural-language queries ('quiet 3-bed near good schools under 600k') that must combine semantic similarity with hard structured filters (price ≤ 600k, beds = 3, status = active) and ranking by recency and proximity. There are ~5M active listings, constantly changing (sold, price-dropped, new). Design a hybrid retrieval system that respects the hard filters exactly while still using semantic matching, and explain why pure vector search alone fails here.

What a strong answer looks like

Clarify scale and constraints first. Propose a clean component breakdown, then go deep on the hard parts — data model, bottlenecks, consistency, failure modes — and name the trade-offs you are making.

Learn the concepts

Narrate your design

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Run or narrate your approach, then ask the coach.