diff --git a/internal/core/src/index/IndexFactory.cpp b/internal/core/src/index/IndexFactory.cpp
index 4a594725ec..90862dffdc 100644
--- a/internal/core/src/index/IndexFactory.cpp
+++ b/internal/core/src/index/IndexFactory.cpp
@@ -308,7 +308,8 @@ IndexFactory::ScalarIndexLoadResource(
             request.max_disk_cost = 0;
         }
         request.has_raw_data = true;
-    } else if (index_type == milvus::index::INVERTED_INDEX_TYPE) {
+    } else if (index_type == milvus::index::INVERTED_INDEX_TYPE ||
+               index_type == milvus::index::NGRAM_INDEX_TYPE) {
         request.final_memory_cost = 0;
         request.final_disk_cost = index_size_in_bytes;
         request.max_memory_cost = index_size_in_bytes;
diff --git a/internal/core/src/index/NgramInvertedIndexTest.cpp b/internal/core/src/index/NgramInvertedIndexTest.cpp
index 04279fbc40..e1b9b03ed4 100644
--- a/internal/core/src/index/NgramInvertedIndexTest.cpp
+++ b/internal/core/src/index/NgramInvertedIndexTest.cpp
@@ -99,6 +99,7 @@ test_ngram_with_data(const boost::container::vector<std::string>& data,
     storage::FileManagerContext ctx(field_meta, index_meta, cm);
     std::vector<std::string> index_files;
 
+    auto index_size = 0;
     {
         Config config;
         config[milvus::index::INDEX_TYPE] = milvus::index::INVERTED_INDEX_TYPE;
@@ -115,9 +116,9 @@ test_ngram_with_data(const boost::container::vector<std::string>& data,
 
         auto create_index_result = index->Upload();
         auto memSize = create_index_result->GetMemSize();
-        auto serializedSize = create_index_result->GetSerializedSize();
+        index_size = create_index_result->GetSerializedSize();
         ASSERT_GT(memSize, 0);
-        ASSERT_GT(serializedSize, 0);
+        ASSERT_GT(index_size, 0);
         index_files = create_index_result->GetIndexFiles();
     }
 
@@ -183,7 +184,7 @@ test_ngram_with_data(const boost::container::vector<std::string>& data,
             .index_params = index_params,
             .index_files = index_files,
             .schema = field_meta.field_schema,
-            .index_size = 1024 * 1024 * 1024,
+            .index_size = index_size,
         };
 
         uint8_t trace_id[16] = {0};
diff --git a/internal/core/unittest/test_loading.cpp b/internal/core/unittest/test_loading.cpp
index 6c59232acd..f7e2c47b62 100644
--- a/internal/core/unittest/test_loading.cpp
+++ b/internal/core/unittest/test_loading.cpp
@@ -239,6 +239,24 @@ INSTANTIATE_TEST_SUITE_P(
              0,
              1 * 1024 * 1024 * 1024,
              false}),
+        std::pair<std::map<std::string, std::string>, LoadResourceRequest>(
+            {{"index_type", "NGRAM"},
+             {"mmap", "false"},
+             {"field_type", "string"}},
+            {1UL * 1024 * 1024 * 1024,
+             1UL * 1024 * 1024 * 1024,
+             0UL,
+             1UL * 1024 * 1024 * 1024,
+             false}),
+        std::pair<std::map<std::string, std::string>, LoadResourceRequest>(
+            {{"index_type", "NGRAM"},
+             {"mmap", "true"},
+             {"field_type", "string"}},
+            {1 * 1024 * 1024 * 1024,
+             1 * 1024 * 1024 * 1024,
+             0,
+             1 * 1024 * 1024 * 1024,
+             false}),
         std::pair<std::map<std::string, std::string>, LoadResourceRequest>(
             {{"index_type", "BITMAP"},
              {"mmap", "false"},