MATCHING FUNNEL FOR LARGE DOCUMENT INDEX

Search results are identified and returned in response to search queries by evaluating and pruning candidate documents in multiple stages. The process employs a search index that indexes atoms found in documents and pre-computed scores for document/atom pairs. When a search query is received, atoms are identified from the search query and a reformulated query is generated based on the identified atoms. The reformulated query is used to identify matching documents, and a preliminary score is generated for matching documents using a simplified scoring function and pre-computed scores in the search index. Documents are pruned based on preliminary scores, and the remaining documents are evaluated using a final ranking algorithm that provides a final set of ranked documents, which is used to generate search results to return in response to the search query.