Fix search error about metric type

Signed-off-by: bigsheeper <yihao.dai@zilliz.com>

internal/core/src/segcore/plan_c.cpp

@@ -75,6 +75,12 @@ GetTopK(CPlan plan) {
     return res;
 }
 
+const char*
+GetMetricType(CPlan plan) {
+    auto query_plan = static_cast<milvus::query::Plan*>(plan);
+    return strdup(query_plan->plan_node_->query_info_.metric_type_.c_str());
+}
+
 void
 DeletePlan(CPlan cPlan) {
     auto plan = (milvus::query::Plan*)cPlan;

internal/core/src/segcore/plan_c.h

@@ -35,6 +35,9 @@ GetNumOfQueries(CPlaceholderGroup placeholder_group);
 int64_t
 GetTopK(CPlan plan);
 
+const char*
+GetMetricType(CPlan plan);
+
 void
 DeletePlan(CPlan plan);
 

internal/core/src/segcore/reduce_c.cpp

@@ -64,6 +64,11 @@ struct SearchResultPair {
         return (distance_ < pair.distance_);
     }
 
+    bool
+    operator>(const SearchResultPair& pair) const {
+        return (distance_ > pair.distance_);
+    }
+
     void
     reset_distance() {
         distance_ = search_result_->result_distances_[offset_];
@@ -89,7 +94,7 @@ GetResultData(std::vector<std::vector<int64_t>>& search_records,
     AssertInfo(topk > 0, "topK must greater than 0");
     for (int i = 0; i < topk; ++i) {
         result_pairs[0].reset_distance();
-        std::sort(result_pairs.begin(), result_pairs.end());
+        std::sort(result_pairs.begin(), result_pairs.end(), std::greater<>());
         auto& result_pair = result_pairs[0];
         auto index = result_pair.index_;
         is_selected[index] = true;

internal/core/src/segcore/segment_c.cpp

@@ -140,6 +140,11 @@ Search(CSegmentBase c_segment,
     auto status = CStatus();
     try {
         auto res = segment->Search(plan, placeholder_groups.data(), timestamps, num_groups, *query_result);
+        if (plan->plan_node_->query_info_.metric_type_ != "IP") {
+            for (auto& dis : query_result->result_distances_) {
+                dis *= -1;
+            }
+        }
         status.error_code = Success;
         status.error_msg = "";
     } catch (std::exception& e) {

internal/proto/internal_msg.proto

@@ -259,6 +259,7 @@ message SearchResult {
     uint64 timestamp = 6;
     int64 result_channelID = 7;
     repeated bytes hits = 8;
+    string metric_type = 9;
 }
 
 message TimeTickMsg {

internal/proxy/task.go

@@ -487,6 +487,7 @@ func (qt *QueryTask) PostExecute() error {
 				Hits: make([][]byte, 0),
 			}
 
+			const minFloat32 = -1 * float32(math.MaxFloat32)
 			for i := 0; i < nq; i++ {
 				locs := make([]int, availableQueryNodeNum)
 				reducedHits := &servicepb.Hits{
@@ -496,18 +497,18 @@ func (qt *QueryTask) PostExecute() error {
 				}
 
 				for j := 0; j < topk; j++ {
-					choice, minDistance := 0, float32(math.MaxFloat32)
+					choice, maxDistance := 0, minFloat32
 					for q, loc := range locs { // query num, the number of ways to merge
 						distance := hits[q][i].Scores[loc]
-						if distance < minDistance {
+						if distance > maxDistance {
 							choice = q
-							minDistance = distance
+							maxDistance = distance
 						}
 					}
 					choiceOffset := locs[choice]
 					// check if distance is valid, `invalid` here means very very big,
 					// in this process, distance here is the smallest, so the rest of distance are all invalid
-					if hits[choice][i].Scores[choiceOffset] >= float32(math.MaxFloat32) {
+					if hits[choice][i].Scores[choiceOffset] <= minFloat32 {
 						break
 					}
 					reducedHits.IDs = append(reducedHits.IDs, hits[choice][i].IDs[choiceOffset])
@@ -517,6 +518,11 @@ func (qt *QueryTask) PostExecute() error {
 					reducedHits.Scores = append(reducedHits.Scores, hits[choice][i].Scores[choiceOffset])
 					locs[choice]++
 				}
+				if searchResults[0].MetricType != "IP" {
+					for k := range reducedHits.Scores {
+						reducedHits.Scores[k] *= -1
+					}
+				}
 				reducedHitsBs, err := proto.Marshal(reducedHits)
 				if err != nil {
 					log.Println("marshal error")

internal/querynode/plan.go

@@ -41,6 +41,13 @@ func (plan *Plan) getTopK() int64 {
 	return int64(topK)
 }
 
+func (plan *Plan) getMetricType() string {
+	cMetricType := C.GetMetricType(plan.cPlan)
+	defer C.free(unsafe.Pointer(cMetricType))
+	metricType := C.GoString(cMetricType)
+	return metricType
+}
+
 func (plan *Plan) delete() {
 	C.DeletePlan(plan.cPlan)
 }

internal/querynode/plan_test.go

@@ -27,6 +27,8 @@ func TestPlan_Plan(t *testing.T) {
 	assert.NotEqual(t, plan, nil)
 	topk := plan.getTopK()
 	assert.Equal(t, int(topk), 10)
+	metricType := plan.getMetricType()
+	assert.Equal(t, metricType, "L2")
 	plan.delete()
 	deleteCollection(collection)
 }

internal/querynode/search_service.go

@@ -336,6 +336,7 @@ func (ss *searchService) search(msg msgstream.TsMsg) error {
 			Timestamp:       searchTimestamp,
 			ResultChannelID: searchMsg.ResultChannelID,
 			Hits:            hits,
+			MetricType:      plan.getMetricType(),
 		}
 		searchResultMsg := &msgstream.SearchResultMsg{
 			BaseMsg:      msgstream.BaseMsg{HashValues: []uint32{uint32(searchMsg.ResultChannelID)}},