anchor.diff:      fetch_start_virtual(Pid, ddSchema, MatchSpec, BlockSize, Opts);
   fetch_start(Pid, ddSize, MatchSpec, BlockSize, Opts) ->
       fetch_start_virtual(Pid, ddSize, MatchSpec, BlockSize, Opts);
  +fetch_start(Pid, snapshot, MatchSpec, BlockSize, Opts) ->
  +    fetch_start_virtual(Pid, snapshot, MatchSpec, BlockSize, Opts);
   fetch_start(Pid, Table, MatchSpec, BlockSize, Opts) ->
       imem_if:fetch_start(Pid, physical_table_name(Table), MatchSpec, BlockSize, Opts).
   
  
positive.code: column_names(Infos)->
      [list_to_atom(lists:flatten(io_lib:format("~p", [N]))) || #ddColumn{name=N} <- Infos].
  
  column_infos(TableAlias) when is_atom(TableAlias) ->
      column_infos({schema(),TableAlias});    
  column_infos({Schema,TableAlias}) when is_binary(Schema), is_binary(TableAlias) ->
  
negative.code:     select_virtual(ddSchema, MatchSpec);
  select(ddSize, MatchSpec) ->
      select_virtual(ddSize, MatchSpec);
  select(snapshot, MatchSpec) ->
      select_virtual(snapshot, MatchSpec);
  select(Table, MatchSpec) ->
      imem_if:select(physical_table_name(Table), MatchSpec).
  
  