SQL. Вывести информацию по данным в Oracle

Вывести информацию по табличным пространствам:
SQL> select b.tablespace_name, tbs_size SizeMb, a.free_space FreeMb

    from (select tablespace_name, round(sum(bytes)/1024/1024 ,2) as free_space

       from dba_free_space

       group by tablespace_name) a,

      (select tablespace_name, sum(bytes)/1024/1024 as tbs_size

       from dba_data_files

       group by tablespace_name) b

    where a.tablespace_name(+)=b.tablespace_name;

Вывести 10 самых больших таблиц:
SQL> SELECT * FROM (
    SELECT owner, segment_name, bytes/1024/1024 meg
    FROM dba_segments
    WHERE segment_type = 'TABLE'
    ORDER BY bytes/1024/1024 desc)
    WHERE rownum <= 10;