diff --git a/cpp/src/core/src/knowhere/index/vector_index/idmap.cpp b/cpp/src/core/src/knowhere/index/vector_index/idmap.cpp
index ba35f8cc494084e849b528225117f8c5bfee43f4..93fdde5cddd559e29f05715b1ff90e96c90c0eff 100644
--- a/cpp/src/core/src/knowhere/index/vector_index/idmap.cpp
+++ b/cpp/src/core/src/knowhere/index/vector_index/idmap.cpp
@@ -39,9 +39,9 @@ DatasetPtr IDMAP::Search(const DatasetPtr &dataset, const Config &config) {
     }
 
     auto k = config["k"].as<size_t>();
-    auto metric_type = config["metric_type"].as_string() == "L2" ?
-                       faiss::METRIC_L2 : faiss::METRIC_INNER_PRODUCT;
-    index_->metric_type = metric_type;
+    //auto metric_type = config["metric_type"].as_string() == "L2" ?
+    //                   faiss::METRIC_L2 : faiss::METRIC_INNER_PRODUCT;
+    //index_->metric_type = metric_type;
 
     GETTENSOR(dataset)