refactor: do some internal refactor.

source/libs/function/src/functionMgt.c

@@ -116,6 +116,11 @@ EFuncDataRequired fmFuncDynDataRequired(int32_t funcId, void* pRes, STimeWindow*
     return TSDB_CODE_FAILED;
   }
 
+  const char* name = funcMgtBuiltins[funcId].name;
+  if ((strcmp(name, "_group_key") == 0) || (strcmp(name, "_select_value") == 0)) {
+    return FUNC_DATA_REQUIRED_NOT_LOAD;
+  }
+
   if (funcMgtBuiltins[funcId].dynDataRequiredFunc == NULL) {
     return FUNC_DATA_REQUIRED_DATA_LOAD;
   } else {