select a.owner, a.table_name, tt.total, a.partitioned

  from dba_tables a,

       (select t.owner,

               t.segment_name,

               trunc(sum(t.bytes) / 1024 / 1024 / 1024) as total

          from dba_segments t

         where t.segment_type like 'TABLE%'

         group by t.owner, t.segment_name

        having sum(t.bytes) / 1024 / 1024 > 1024) tt

 where a.owner = tt.owner

   and a.table_name = tt.segment_name;