select t.table_name table_name,  
       t.table_size table_size_KB,  
       i.index_name index_name,  
       i.index_size index_size_KB  
  from (select segment_name table_name,   
               ceil(sum(bytes) / 1024) table_size  
          from dba_segments  
         where owner like '<Пользователь>'  
           and segment_type = 'TABLE'  
           and segment_name = '<Имя сегдента>'  
         group by segment_name) t  
  left join dba_indexes ti  
    on ti.table_name = t.table_name  
  left join (select segment_name index_name,  
                    ceil(sum(bytes) / 1024) index_size  
               from dba_segments  
              where owner like '<Пользователь>'  
                and segment_type = 'INDEX'  
              group by segment_name) i  
    on i.index_name = ti.index_name  
 order by i.index_size desc