diff --git a/internal/querynodev2/delegator/delegator.go b/internal/querynodev2/delegator/delegator.go
index 81970e6566..0a3f6cbfe7 100644
--- a/internal/querynodev2/delegator/delegator.go
+++ b/internal/querynodev2/delegator/delegator.go
@@ -98,7 +98,7 @@ type shardDelegator struct {
 	tsafeManager   tsafe.Manager
 	pkOracle       pkoracle.PkOracle
 	// L0 delete buffer
-	deleteMut    sync.Mutex
+	deleteMut    sync.RWMutex
 	deleteBuffer deletebuffer.DeleteBuffer[*deletebuffer.Item]
 	// dispatcherClient msgdispatcher.Client
 	factory msgstream.Factory
diff --git a/internal/querynodev2/delegator/delegator_data.go b/internal/querynodev2/delegator/delegator_data.go
index f03f65baa0..bc45a0ebff 100644
--- a/internal/querynodev2/delegator/delegator_data.go
+++ b/internal/querynodev2/delegator/delegator_data.go
@@ -433,8 +433,8 @@ func (sd *shardDelegator) loadStreamDelete(ctx context.Context,
 		return candidate.ID(), candidate
 	})
 
-	sd.deleteMut.Lock()
-	defer sd.deleteMut.Unlock()
+	sd.deleteMut.RLock()
+	defer sd.deleteMut.RUnlock()
 	// apply buffered delete for new segments
 	// no goroutines here since qnv2 has no load merging logic
 	for _, info := range infos {