From 8d193a3e56d040c474fa78a5d06fa927633101a6 Mon Sep 17 00:00:00 2001
From: Jiquan Long <jiquan.long@zilliz.com>
Date: Tue, 27 Jun 2023 19:22:45 +0800
Subject: [PATCH] Skip unnecessary reduce phase during search (#25166)

Signed-off-by: longjiquan <jiquan.long@zilliz.com>
---
 internal/querynodev2/delegator/delegator.go  |  4 ++--
 internal/querynodev2/segments/result.go      |  8 +++++++
 tests/integration/jsonexpr/json_expr_test.go | 24 +++++++++++++++-----
 3 files changed, 28 insertions(+), 8 deletions(-)

diff --git a/internal/querynodev2/delegator/delegator.go b/internal/querynodev2/delegator/delegator.go
index 80c519f1b6..58569212a1 100644
--- a/internal/querynodev2/delegator/delegator.go
+++ b/internal/querynodev2/delegator/delegator.go
@@ -253,7 +253,7 @@ func (sd *shardDelegator) Search(ctx context.Context, req *querypb.SearchRequest
 		return nil, err
 	}
 
-	log.Info("Delegator search done")
+	log.Debug("Delegator search done")
 
 	return results, nil
 }
@@ -484,7 +484,7 @@ func (sd *shardDelegator) waitTSafe(ctx context.Context, ts uint64) error {
 	lag := gt.Sub(st)
 	maxLag := paramtable.Get().QueryNodeCfg.MaxTimestampLag.GetAsDuration(time.Second)
 	if lag > maxLag {
-		log.Warn("guarantee and servicable ts larger than MaxLag",
+		log.Warn("guarantee and serviceable ts larger than MaxLag",
 			zap.Time("guaranteeTime", gt),
 			zap.Time("serviceableTime", st),
 			zap.Duration("lag", lag),
diff --git a/internal/querynodev2/segments/result.go b/internal/querynodev2/segments/result.go
index 8a4fa1450c..bc55071020 100644
--- a/internal/querynodev2/segments/result.go
+++ b/internal/querynodev2/segments/result.go
@@ -40,6 +40,14 @@ var _ typeutil.ResultWithID = &internalpb.RetrieveResults{}
 var _ typeutil.ResultWithID = &segcorepb.RetrieveResults{}
 
 func ReduceSearchResults(ctx context.Context, results []*internalpb.SearchResults, nq int64, topk int64, metricType string) (*internalpb.SearchResults, error) {
+	results = lo.Filter(results, func(result *internalpb.SearchResults, _ int) bool {
+		return result != nil && result.GetSlicedBlob() != nil
+	})
+
+	if len(results) == 1 {
+		return results[0], nil
+	}
+
 	log := log.Ctx(ctx)
 
 	searchResultData, err := DecodeSearchResults(results)
diff --git a/tests/integration/jsonexpr/json_expr_test.go b/tests/integration/jsonexpr/json_expr_test.go
index db973da499..edacac9f10 100644
--- a/tests/integration/jsonexpr/json_expr_test.go
+++ b/tests/integration/jsonexpr/json_expr_test.go
@@ -207,7 +207,9 @@ func (s *JSONExprSuite) TestJSON_InsertWithoutDynamicData() {
 	// search
 	expr = `$meta["A"] > 90`
 	checkFunc := func(result *milvuspb.SearchResults) {
-		s.Equal(0, len(result.Results.FieldsData))
+		for _, f := range result.Results.GetFieldsData() {
+			s.Nil(f)
+		}
 	}
 	s.doSearch(collectionName, []string{common.MetaFieldName}, expr, dim, checkFunc)
 	log.Info("GT expression run successfully")
@@ -563,7 +565,9 @@ func (s *JSONExprSuite) checkSearch(collectionName, fieldName string, dim int) {
 
 	expr = `exists AAA`
 	checkFunc = func(result *milvuspb.SearchResults) {
-		s.Equal(0, len(result.Results.FieldsData))
+		for _, f := range result.Results.GetFieldsData() {
+			s.Nil(f)
+		}
 	}
 	s.doSearch(collectionName, []string{fieldName}, expr, dim, checkFunc)
 	log.Info("EXISTS expression run successfully")
@@ -610,7 +614,9 @@ func (s *JSONExprSuite) checkSearch(collectionName, fieldName string, dim int) {
 
 	expr = `A like "10"`
 	checkFunc = func(result *milvuspb.SearchResults) {
-		s.Equal(0, len(result.Results.FieldsData))
+		for _, f := range result.Results.GetFieldsData() {
+			s.Nil(f)
+		}
 	}
 	s.doSearch(collectionName, []string{fieldName}, expr, dim, checkFunc)
 	log.Info("like expression run successfully")
@@ -627,14 +633,18 @@ func (s *JSONExprSuite) checkSearch(collectionName, fieldName string, dim int) {
 
 	expr = `str1 like 'abc"def-%'`
 	checkFunc = func(result *milvuspb.SearchResults) {
-		s.Equal(0, len(result.Results.FieldsData))
+		for _, f := range result.Results.GetFieldsData() {
+			s.Nil(f)
+		}
 	}
 	s.doSearch(collectionName, []string{fieldName}, expr, dim, checkFunc)
 	log.Info("like expression run successfully")
 
 	expr = `str2 like 'abc\"def-%'`
 	checkFunc = func(result *milvuspb.SearchResults) {
-		s.Equal(0, len(result.Results.FieldsData))
+		for _, f := range result.Results.GetFieldsData() {
+			s.Nil(f)
+		}
 	}
 	s.doSearch(collectionName, []string{fieldName}, expr, dim, checkFunc)
 	log.Info("like expression run successfully")
@@ -651,7 +661,9 @@ func (s *JSONExprSuite) checkSearch(collectionName, fieldName string, dim int) {
 
 	expr = `A in []`
 	checkFunc = func(result *milvuspb.SearchResults) {
-		s.Equal(0, len(result.Results.FieldsData))
+		for _, f := range result.Results.GetFieldsData() {
+			s.Nil(f)
+		}
 	}
 	s.doSearch(collectionName, []string{fieldName}, expr, dim, checkFunc)
 	log.Info("term empty expression run successfully")