anchor.diff:  
   %%-------------------------------------------------------------------
   %% @doc
  -%% Prepares document for new import scan.
  +%% Prepares existing document for new import scan.
  +%% This function assumes that document has already been created by
  +%% ?MODULE:ensure_created/2 function.
   %% It resets control counters, and increases to_process counter and
   %% queue_length histograms by 1.
   %% This function also sets scan start_time.
  
positive.code:         {ok, true} ->
              ok;
          {ok, false} ->
              {ok, _} = datastore_model:create(?CTX, new_doc(SpaceId, StorageId)),
              ok;
          Error  ->
              ?error("Failed to check if storage_sync_monitoring document for space ~p and storage ~p exists due to ~p",
                  [SpaceId, StorageId, Error])
  
negative.code: %%-------------------------------------------------------------------
  %% @doc
  %% Prepares document for new update scan.
  %% This function assumes that document has already been created by
  %% ?MODULE:ensure_created/2 function.
  %% It resets control counters, and increases to_process counter and
  %% queue_length histograms by 1.
  %% This function also sets scan start_time.
  