refactor: make Reranker stateless with std::variant value semantics (… - #471
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June 8, 2026 03:33
…libaba#461) Replace class hierarchy (Reranker/ScoreBasedReranker/RrfReranker/ WeightedReranker/CallbackReranker) with std::variant<RrfParams, WeightedParams, CallbackParams> value type and a stateless free function reranker::rerank(). Key changes: - reranker.h: define RerankParams variant + reranker::rerank() API - query.h: MultiQuery::reranker (shared_ptr) -> MultiQuery::rerank (value) - schema.h: add CollectionSchema::get_field_ptr() returning FieldSchema::Ptr - collection.cc: push field lookup to caller, pass vector<FieldSchema::Ptr> - c_api: remove opaque zvec_reranker_t, add zvec_multi_query_set_rerank_* - python binding: expose _RrfParams/_WeightedParams/_CallbackParams + setters - python layer: WeightedReRanker(list[float]), remove Python rerank logic - all tests updated to new interface Benefits: - Thread-safe by design: no mutable state, safe to share across threads - Collection-decoupled: no bind_schema(), field info passed as parameter - Simpler lifecycle: value semantics, no shared_ptr management Closes alibaba#461
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After the reranker stateless refactor the C++ MultiQuery rerank strategy uses a std::variant with a default value, so the implicit 'reranker required' validation no longer triggered. Restore the check in QueryExecutor._execute_multi_query so that a hybrid (multi-query) request without a reranker raises ValueError.
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egolearner
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Jun 8, 2026
Replace dynamic_cast nullptr check with explicit IndexType::FTS check and map FTS/BM25 positive scores to (0.0, 1.0) via 2*atan(score)/pi.
…lify usages Move RrfParams, WeightedParams, CallbackParams and RerankParams into the zvec::reranker namespace, and add explicit reranker:: qualification at all usage sites outside the reranker module (query.h, python/c bindings, tests).
…archQuery> directly
…ImplementedError Remove @AbstractMethod from RerankFunction._to_cpp_params and provide a default implementation raising NotImplementedError. Drop the redundant _to_cpp_params overrides from Qwen and Sentence rerankers since they use the Python rerank path and don't need the C++ conversion.
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…#461)
Replace class hierarchy (Reranker/ScoreBasedReranker/RrfReranker/ WeightedReranker/CallbackReranker) with std::variant<RrfParams, WeightedParams, CallbackParams> value type and a stateless free function reranker::rerank().
Key changes:
Benefits:
Closes #461