diff --git a/internal/querynode/query_shard.go b/internal/querynode/query_shard.go
index e477669503..dcfd204bb7 100644
--- a/internal/querynode/query_shard.go
+++ b/internal/querynode/query_shard.go
@@ -223,14 +223,21 @@ func (q *queryShard) getNewTSafe(tp tsType) (Timestamp, error) {
 }
 
 func (q *queryShard) waitUntilServiceable(ctx context.Context, guaranteeTs Timestamp, tp tsType) {
+	st := q.getServiceableTime(tp)
+	log.Debug("serviceable check start", zap.String("tsType", tp.String()), zap.Uint64("guarantee ts", guaranteeTs), zap.Uint64("serviceable ts", st), zap.String("channel", q.channel))
+	serviceable := func() bool {
+		st = q.getServiceableTime(tp)
+		return st >= guaranteeTs
+	}
+
 	q.watcherCond.L.Lock()
 	defer q.watcherCond.L.Unlock()
-	st := q.getServiceableTime(tp)
-	for guaranteeTs > st {
+	for !serviceable() {
 		log.Debug("serviceable ts before guarantee ts", zap.Uint64("serviceable ts", st), zap.Uint64("guarantee ts", guaranteeTs), zap.String("channel", q.channel))
 		q.watcherCond.Wait()
 		if err := ctx.Err(); err != nil {
-			log.Warn("waitUntialServiceable timeout", zap.Uint64("serviceable ts", st), zap.Uint64("guarantee ts", guaranteeTs), zap.String("channel", q.channel))
+			log.Warn("waitUntilServiceable timeout", zap.Uint64("serviceable ts", st), zap.Uint64("guarantee ts", guaranteeTs), zap.String("channel", q.channel))
+			// TODO: implement timeout logic
 			return
 		}
 		st = q.getServiceableTime(tp)
@@ -390,9 +397,8 @@ func (q *queryShard) searchLeader(ctx context.Context, req *querypb.SearchReques
 
 	go func() {
 		defer wg.Done()
-		// hold request until guarantee timestamp >= service timestamp
 		guaranteeTs := req.GetReq().GetGuaranteeTimestamp()
-		q.waitUntilServiceable(ctx, guaranteeTs, tsTypeDML)
+		q.waitUntilServiceable(ctx, guaranteeTs, tsTypeDML) // wait until guarantee timestamp >= service timestamp
 		// shard leader queries its own streaming data
 		// TODO add context
 		sResults, _, _, sErr := q.streaming.search(searchRequests, collectionID, partitionIDs, req.DmlChannel, plan, timestamp)
@@ -419,13 +425,13 @@ func (q *queryShard) searchLeader(ctx context.Context, req *querypb.SearchReques
 		MetricType:     plan.getMetricType(),
 		NumQueries:     queryNum,
 		TopK:           topK,
-		SlicedBlob:     nil,
+		SlicedBlob:     nil, // placeholder for serialized streaming result
 		SlicedOffset:   1,
 		SlicedNumCount: 1,
 	})
 
+	// reduce streaming results and transform to blob
 	if len(streamingResults) > 0 {
-		// reduce search results
 		numSegment := int64(len(streamingResults))
 		err = reduceSearchResultsAndFillData(plan, streamingResults, numSegment)
 		if err != nil {
@@ -615,22 +621,10 @@ func reduceSearchResultData(searchResultData []*schemapb.SearchResultData, nq in
 			}
 			offsets[sel]++
 		}
-
-		// if realTopK != -1 && realTopK != j {
-		// 	log.Warn("Proxy Reduce Search Result", zap.Error(errors.New("the length (topk) between all result of query is different")))
-		// 	// return nil, errors.New("the length (topk) between all result of query is different")
-		// }
 		ret.Topks = append(ret.Topks, j)
 	}
 	log.Debug("skip duplicated search result", zap.Int64("count", skipDupCnt), zap.Any("ret", ret))
-	// ret.TopK = realTopK
-
-	// if !distance.PositivelyRelated(metricType) {
-	// 	for k := range ret.Scores {
-	// 		ret.Scores[k] *= -1
-	// 	}
-	// }
-
+	// Note: query shard does not check whether the metricType is positively related, proxy will do the job
 	return ret, nil
 }
 
@@ -901,6 +895,7 @@ func mergeInternalRetrieveResults(retrieveResults []*internalpb.RetrieveResults)
 	return ret, nil
 }
 
+// printSearchResultData is for debug usage
 // func printSearchResultData(data *schemapb.SearchResultData, header string) {
 // 	size := len(data.Ids.GetIntId().Data)
 // 	if size != len(data.Scores) {