diff --git a/src/Functions/globalVariable.cpp b/src/Functions/globalVariable.cpp
index 55561af4d10..68b71eebff0 100644
--- a/src/Functions/globalVariable.cpp
+++ b/src/Functions/globalVariable.cpp
@@ -77,8 +77,10 @@ private:
         DataTypePtr type;
         Field value;
     };
-    std::unordered_map<String, TypeAndValue> global_variable_map = {
-        {"max_allowed_packet", {std::make_shared<DataTypeInt32>(), 67108864}}, {"version", {std::make_shared<DataTypeString>(), "5.7.30"}}};
+    std::unordered_map<String, TypeAndValue> global_variable_map
+        = {{"max_allowed_packet", {std::make_shared<DataTypeInt32>(), 67108864}},
+           {"version", {std::make_shared<DataTypeString>(), "5.7.30"}},
+           {"transaction_isolation", {std::make_shared<DataTypeString>(), "READ-UNCOMMITTED"}}};
 };
 
 }