diff --git a/core/src/index/knowhere/knowhere/index/vector_index/IndexAnnoy.cpp b/core/src/index/knowhere/knowhere/index/vector_index/IndexAnnoy.cpp
index d0b966b51b..042b7a55e0 100644
--- a/core/src/index/knowhere/knowhere/index/vector_index/IndexAnnoy.cpp
+++ b/core/src/index/knowhere/knowhere/index/vector_index/IndexAnnoy.cpp
@@ -85,6 +85,7 @@ void
 IndexAnnoy::BuildAll(const DatasetPtr& dataset_ptr, const Config& config) {
     if (index_) {
         // it is builded all
+        KNOWHERE_LOG_DEBUG << "IndexAnnoy::BuildAll: index_ has been built!";
         return;
     }