diff --git a/docs/examples/python/mockdatasoruce.py b/docs/examples/python/mockdatasoruce.py
index 6172fda7b399d9a6c570360baa568115698f0611..12c18e57f13aebdf4bd0481845c2b31a93f6d63f 100644
--- a/docs/examples/python/mockdatasoruce.py
+++ b/docs/examples/python/mockdatasoruce.py
@@ -39,7 +39,7 @@ class MockDataSource:
         ts = []
         for _ in range(1000):
             self.current_ts += 100
-            ts.append(self.current_ts)
+            ts.append(str(self.current_ts))
         # add timestamp to each row
         # [(tableId, ["tableName,ts,current,voltage,phase,location,groupId"])]
         result = []