Refactor API name: modifyRequestSize -> adjustRequestSizeForKNN, etc.

index_alias_impl.go

@@ -454,7 +454,7 @@ func MultiSearch(ctx context.Context, req *SearchRequest, indexes ...Index) (*Se
 	}
 	originalSize := req.Size
 	if len(indexes) > 1 {
-		modifyRequestSize(req, len(indexes))
+		req.Size = adjustRequestSizeForKNN(req, len(indexes))
 	}
 
 	// run search on each index in separate go routine

search/scorer/scorer_knn.go

@@ -26,8 +26,6 @@ import (
 
 var reflectStaticSizeKNNQueryScorer int
 
-const MaxAllowedScore = 10000.0
-
 func init() {
 	var sqs KNNQueryScorer
 	reflectStaticSizeKNNQueryScorer = int(reflect.TypeOf(sqs).Size())
@@ -62,22 +60,26 @@ func NewKNNQueryScorer(queryVector []float32, queryField string, queryBoost floa
 	}
 }
 
+// TODO: Better value needed here?
+const maxEuclideanDistance = 100000.0
+
 func (sqs *KNNQueryScorer) Score(ctx *search.SearchContext,
 	knnMatch *index.VectorDoc) *search.DocumentMatch {
 	rv := ctx.DocumentMatchPool.Get()
 
 	if sqs.includeScore || sqs.options.Explain {
 		var scoreExplanation *search.Explanation
 		score := knnMatch.Score
-		if score == 0.0 {
-			// the vector is found to be exactly same as the query vector
-			// this is a perfect match, so return the max score
-			score = MaxAllowedScore
-		} else if sqs.similarityMetric == index.EuclideanDistance {
-			// safeguard from divide-by-zero
-			// euclidean distances need to be inverted to work
-			// tf-idf scoring
-			score = 1.0 / score
+		if sqs.similarityMetric == index.EuclideanDistance {
+			// in case of euclidean distance being the distance metric,
+			// an exact vector (perfect match), would return distance = 0
+			if score == 0 {
+				score = maxEuclideanDistance
+			} else {
+				// euclidean distances need to be inverted to work with
+				// tf-idf scoring
+				score = 1.0 / score
+			}
 		}
 
 		// if the query weight isn't 1, multiply

search/util.go

@@ -106,7 +106,6 @@ const (
 const SearchIncrementalCostKey = "_search_incremental_cost_key"
 const QueryTypeKey = "_query_type_key"
 const FuzzyMatchPhraseKey = "_fuzzy_match_phrase_key"
-const AliasPartitionedModeKey = "_alias_partitioned_mode_key"
 
 func RecordSearchCost(ctx context.Context,
 	msg SearchIncrementalCostCallbackMsg, bytes uint64) {

search_knn.go

@@ -181,17 +181,22 @@ func mergeKNNResults(req *SearchRequest, sr *SearchResult) {
 	}
 }
 
-func modifyRequestSize(req *SearchRequest, numIndexes int) {
-	if len(req.KNN) > 0 {
-		var minSizeReq int64
-		for _, knn := range req.KNN {
-			minSizeReq += knn.K
-		}
-		minSizeReq *= int64(numIndexes)
-		if int64(req.Size) < minSizeReq {
-			req.Size = int(minSizeReq)
+func adjustRequestSizeForKNN(req *SearchRequest, numIndexPartitions int) int {
+	var adjustedSize int
+	if req != nil {
+		adjustedSize = req.Size
+		if len(req.KNN) > 0 {
+			var minSizeReq int64
+			for _, knn := range req.KNN {
+				minSizeReq += knn.K
+			}
+			minSizeReq *= int64(numIndexPartitions)
+			if int64(adjustedSize) < minSizeReq {
+				adjustedSize = int(minSizeReq)
+			}
 		}
 	}
+	return adjustedSize
 }
 
 // heap impl

search_no_knn.go

@@ -153,7 +153,12 @@ func validateKNN(req *SearchRequest) error {
 }
 
 func mergeKNNResults(req *SearchRequest, sr *SearchResult) {
+	// no-op
 }
 
-func modifyRequestSize(req *SearchRequest, numPartitions int) {
+func adjustRequestSizeForKNN(req *SearchRequest, numIndexPartitions int) int {
+	if req != nil {
+		return req.Size
+	}
+	return 0
 }