Added example for async execute query (#537)

Added examples and fixed the async execute not working without pyarrow

Signed-off-by: varun-edachali-dbx <[email protected]>

Author: jprakash-db

src/databricks/sql/client.py

@@ -876,6 +876,19 @@ def is_query_pending(self):
             ttypes.TOperationState.PENDING_STATE,
         ]
 
+    def is_query_pending(self):
+        """
+        Checks whether the async executing query is in pending state or not
+
+        :return:
+        """
+        operation_state = self.get_query_state()
+
+        return not operation_state or operation_state in [
+            ttypes.TOperationState.RUNNING_STATE,
+            ttypes.TOperationState.PENDING_STATE,
+        ]
+
     def get_async_execution_result(self):
         """