diff --git a/flex/storages/rt_mutable_graph/loading_config.cc b/flex/storages/rt_mutable_graph/loading_config.cc
index 7817637873cf..3ef8aa93817c 100644
--- a/flex/storages/rt_mutable_graph/loading_config.cc
+++ b/flex/storages/rt_mutable_graph/loading_config.cc
@@ -835,6 +835,9 @@ int32_t LoadingConfig::GetBatchSize() const {
 }
 
 bool LoadingConfig::GetIsBatchReader() const {
+  if (metadata_.find(reader_options::BATCH_READER) == metadata_.end()) {
+    return reader_options::DEFAULT_BATCH_READER;
+  }
   auto str = metadata_.at(reader_options::BATCH_READER);
   return str == "true" || str == "True" || str == "TRUE";
 }
diff --git a/flex/storages/rt_mutable_graph/loading_config.h b/flex/storages/rt_mutable_graph/loading_config.h
index 04c3754838e9..39135d003771 100644
--- a/flex/storages/rt_mutable_graph/loading_config.h
+++ b/flex/storages/rt_mutable_graph/loading_config.h
@@ -36,6 +36,8 @@ namespace gs {
 
 namespace reader_options {
 static const int32_t DEFAULT_BLOCK_SIZE = (1 << 20);  // 1MB
+static const bool DEFAULT_BATCH_READER =
+    false;  // By default, we read the whole table at once.
 
 // KEY_WORDS for configurations
 static const char* DELIMITER = "delimiter";