use shallow copy and add comments

Author: Linchin

google/cloud/bigquery/client.py

@@ -2041,7 +2041,6 @@ def _get_query_results(
             query_params=extra_params,
             timeout=timeout,
         )
-        breakpoint()
         return _QueryResults.from_api_repr(resource)
 
     def job_from_resource(
@@ -4148,7 +4147,6 @@ def _list_rows_from_query_results(
             params["startIndex"] = start_index
 
         params["formatOptions.useInt64Timestamp"] = True
-        # breakpoint()
         row_iterator = RowIterator(
             client=self,
             api_request=functools.partial(self._call_api, retry, timeout=timeout),

google/cloud/bigquery/table.py

@@ -1991,8 +1991,13 @@ def _get_next_page_response(self):
             return response
 
         params = self._get_query_params()
-        import copy
-        params_copy = copy.deepcopy(params)
+
+        # If the user has provided page_size and start_index, we need to pass
+        # start_index for the first page, but for all subsequent pages, we
+        # should not pass start_index. We make a shallow copy of params and do
+        # not alter the original, so if the user iterates the results again,
+        # start_index is preserved.
+        params_copy = copy.copy(params)
         if self._page_size is not None:
             if self.page_number and "startIndex" in params:
                 del params_copy["startIndex"]