Adding upstream version 2.5.1.

Signed-off-by: Daniel Baumann <daniel@debian.org>

search/query/knn.go

@@ -0,0 +1,95 @@
+//  Copyright (c) 2023 Couchbase, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// 		http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//go:build vectors
+// +build vectors
+
+package query
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+
+	"github.com/blevesearch/bleve/v2/mapping"
+	"github.com/blevesearch/bleve/v2/search"
+	"github.com/blevesearch/bleve/v2/search/searcher"
+	index "github.com/blevesearch/bleve_index_api"
+)
+
+type KNNQuery struct {
+	VectorField string    `json:"field"`
+	Vector      []float32 `json:"vector"`
+	K           int64     `json:"k"`
+	BoostVal    *Boost    `json:"boost,omitempty"`
+
+	// see KNNRequest.Params for description
+	Params json.RawMessage `json:"params"`
+	// elegibleSelector is used to filter out documents that are
+	// eligible for the KNN search from a pre-filter query.
+	elegibleSelector index.EligibleDocumentSelector
+}
+
+func NewKNNQuery(vector []float32) *KNNQuery {
+	return &KNNQuery{Vector: vector}
+}
+
+func (q *KNNQuery) Field() string {
+	return q.VectorField
+}
+
+func (q *KNNQuery) SetK(k int64) {
+	q.K = k
+}
+
+func (q *KNNQuery) SetFieldVal(field string) {
+	q.VectorField = field
+}
+
+func (q *KNNQuery) SetBoost(b float64) {
+	boost := Boost(b)
+	q.BoostVal = &boost
+}
+
+func (q *KNNQuery) Boost() float64 {
+	return q.BoostVal.Value()
+}
+
+func (q *KNNQuery) SetParams(params json.RawMessage) {
+	q.Params = params
+}
+
+func (q *KNNQuery) SetEligibleSelector(eligibleSelector index.EligibleDocumentSelector) {
+	q.elegibleSelector = eligibleSelector
+}
+
+func (q *KNNQuery) Searcher(ctx context.Context, i index.IndexReader,
+	m mapping.IndexMapping, options search.SearcherOptions) (search.Searcher, error) {
+	fieldMapping := m.FieldMappingForPath(q.VectorField)
+	similarityMetric := fieldMapping.Similarity
+	if similarityMetric == "" {
+		similarityMetric = index.DefaultVectorSimilarityMetric
+	}
+	if q.K <= 0 || len(q.Vector) == 0 {
+		return nil, fmt.Errorf("k must be greater than 0 and vector must be non-empty")
+	}
+	if similarityMetric == index.CosineSimilarity {
+		// normalize the vector
+		q.Vector = mapping.NormalizeVector(q.Vector)
+	}
+
+	return searcher.NewKNNSearcher(ctx, i, m, options, q.VectorField,
+		q.Vector, q.K, q.BoostVal.Value(), similarityMetric, q.Params,
+		q.elegibleSelector)
+}