sq-poller: store previous result if there aren't changes

Signed-off-by: Claudio Lorina <[email protected]>

Author: claudiolor

suzieq/poller/worker/services/service.py

@@ -628,6 +628,7 @@ async def commit_data(self, result: Dict, namespace: str, hostname: str):
                 hostname=[hostname],
                 namespace=[namespace]).query('active')
             prev_res = df.to_dict('records')
+            self.previous_results[key] = prev_res
 
         if result or prev_res:
             adds, dels = self.get_diff(prev_res, result)