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// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
#pragma once
#include "blueprint.h"
#include "nearest_neighbor_distance_heap.h"
#include <vespa/searchlib/tensor/distance_function.h>
#include <vespa/searchlib/tensor/nearest_neighbor_index.h>
#include <optional>
namespace search::tensor { class ITensorAttribute; }
namespace vespalib::eval { struct Value; }
namespace search::queryeval {
/**
* Blueprint for nearest neighbor search iterator.
*
* The search iterator matches the K nearest neighbors in a multi-dimensional vector space,
* where the query point and document points are dense tensors of order 1.
*/
class NearestNeighborBlueprint : public ComplexLeafBlueprint {
public:
enum class Algorithm {
BRUTE_FORCE,
BRUTE_FORCE_FALLBACK,
INDEX_TOP_K,
INDEX_TOP_K_WITH_FILTER
};
private:
const tensor::ITensorAttribute& _attr_tensor;
std::unique_ptr<vespalib::eval::Value> _query_tensor;
uint32_t _target_num_hits;
bool _approximate;
uint32_t _explore_additional_hits;
double _distance_threshold;
double _global_filter_lower_limit;
double _global_filter_upper_limit;
search::tensor::DistanceFunction::UP _fallback_dist_fun;
const search::tensor::DistanceFunction *_dist_fun;
mutable NearestNeighborDistanceHeap _distance_heap;
std::vector<search::tensor::NearestNeighborIndex::Neighbor> _found_hits;
Algorithm _algorithm;
std::shared_ptr<const GlobalFilter> _global_filter;
bool _global_filter_set;
std::optional<uint32_t> _global_filter_hits;
std::optional<double> _global_filter_hit_ratio;
void perform_top_k(const search::tensor::NearestNeighborIndex* nns_index);
public:
NearestNeighborBlueprint(const queryeval::FieldSpec& field,
const tensor::ITensorAttribute& attr_tensor,
std::unique_ptr<vespalib::eval::Value> query_tensor,
uint32_t target_num_hits, bool approximate, uint32_t explore_additional_hits,
double distance_threshold,
double global_filter_lower_limit,
double global_filter_upper_limit);
NearestNeighborBlueprint(const NearestNeighborBlueprint&) = delete;
NearestNeighborBlueprint& operator=(const NearestNeighborBlueprint&) = delete;
~NearestNeighborBlueprint();
const tensor::ITensorAttribute& get_attribute_tensor() const { return _attr_tensor; }
const vespalib::eval::Value& get_query_tensor() const { return *_query_tensor; }
uint32_t get_target_num_hits() const { return _target_num_hits; }
void set_global_filter(const GlobalFilter &global_filter) override;
Algorithm get_algorithm() const { return _algorithm; }
double get_distance_threshold() const { return _distance_threshold; }
std::unique_ptr<SearchIterator> createLeafSearch(const search::fef::TermFieldMatchDataArray& tfmda,
bool strict) const override;
void visitMembers(vespalib::ObjectVisitor& visitor) const override;
bool always_needs_unpack() const override;
};
std::ostream&
operator<<(std::ostream& out, NearestNeighborBlueprint::Algorithm algorithm);
}
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