diff --git a/cpp/src/core/cmake/ThirdPartyPackages.cmake b/cpp/src/core/cmake/ThirdPartyPackages.cmake
index 945f50fb73d080e836b35f13584fc1726dc5b7ed..2ec0c3a41824d6e3bd4a8c5dd0c5013943a80fbc 100644
--- a/cpp/src/core/cmake/ThirdPartyPackages.cmake
+++ b/cpp/src/core/cmake/ThirdPartyPackages.cmake
@@ -261,7 +261,7 @@ else()
     message(STATUS ${FAISS_SOURCE_URL})
 endif()
 # set(FAISS_MD5 "a589663865a8558205533c8ac414278c")
-set(FAISS_MD5 "31167ecbd1903fec600dc4ac00b9be9e")
+set(FAISS_MD5 "57da9c4f599cc8fa4260488b1c96e1cc")
 
 if(DEFINED ENV{KNOWHERE_ARROW_URL})
     set(ARROW_SOURCE_URL "$ENV{KNOWHERE_ARROW_URL}")
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 8f068f72de7bb6771e5dead2a647e03e007198a2..ba35f8cc494084e849b528225117f8c5bfee43f4 100644
--- a/cpp/src/core/src/knowhere/index/vector_index/idmap.cpp
+++ b/cpp/src/core/src/knowhere/index/vector_index/idmap.cpp
@@ -39,6 +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;
 
     GETTENSOR(dataset)