Why Search Breaks in Production

Originally published on Searchplex Blog Similar-looking search systems can behave very differently in production. Take two search systems. Both have an index of around 100k docs. One is a search system for construction and civil engineering documents. Queries look like latest approved floor plan for basement mechanical room . Another is an ecommerce search system. Queries look like waterproof hiking shoes size 11 under 150, in stock, sorted by rating . Both support hybrid search, filters, reranking - so, same broad feature set. But they behave differently in the production. Document count is often considered an useful proxy for scale, but that explains only part of the system's behavior. The difference comes from the interaction of the six factors in the search engine: query shape, document shape, retrieval scope, execution shape, operating pressure, and product contract. Search systems are more than retrieval At the interface boundary, search can look simple: query -> index lookup ->