anchor.diff:        Val = binary_to_term(ValBin),
         {ok, Meta#{ Key => Val }}
       end,
  -    #{<<"last_rid">> => 0,
  -      <<"docs_count">> => 0,
  +    #{<<"docs_count">> => 0,
         <<"system_docs_count">> => 0},
       []
     ),
  -  Meta#{ <<"updated_seq">> => last_sequence(Store) }.
  +  Meta#{ <<"last_rid" >> => last_rid(Store),
  +         <<"updated_seq">> => last_sequence(Store) }.
   
   init_properties() ->
     Props = [{num_docs_updated, 0}],
  
positive.code:       Error
    end.
  
  
  last_sequence(Store) ->
    Prefix = barrel_keys:prefix(seq),
  
negative.code:   ok.
  
  
  do_update_docs(DocBuckets, Db =  #db{id=DbId, store=Store }) ->
    %% try to collect a maximum of updates at once
    DocBuckets2 = collect_updates(DbId, DocBuckets),
    erlang:put(num_docs_updated, maps:size(DocBuckets2)),
  
    {Updates, NewRid, _, OldDocs} = merge_revtrees(DocBuckets2, Db),
  
    lists:foldl(
      fun
  