How to add column to compressed table

Question

Hi gurus,
Can any one help me how to add a column to compressed tables
Thanks in advance

Answer 1

The only difference is if added column has default value. In that case:
SQL> create table tbl(id number,val varchar2(10))
  2  /
Table created.
SQL> insert into tbl
  2  select level,lpad('X',10,'X')
  3  from dual
  4  connect by level <= 100000
  5  /
100000 rows created.
SQL> select bytes
  2  from user_segments
  3  where segment_name = 'TBL'
  4  /
     BYTES
   3145728
SQL> alter table tbl move compress
  2  /
Table altered.
SQL> select bytes
  2  from user_segments
  3  where segment_name = 'TBL'
  4  /
     BYTES
   2097152
SQL> alter table tbl add name varchar2(5) default 'NONE'
  2  /
alter table tbl add name varchar2(5) default 'NONE'
ERROR at line 1:
ORA-39726: unsupported add/drop column operation on compressed tables
SQL> alter table tbl add name varchar2(5)
  2  /
Table altered.
SQL> update tbl set name = 'NONE'
  2  /
100000 rows updated.
SQL> commit
  2  /
Commit complete.
SQL> select bytes
  2  from user_segments
  3  where segment_name = 'TBL'
  4  /
     BYTES
   7340032
SQL> select compression from user_tables where table_name = 'TBL'
  2  /
COMPRESS
ENABLED
SQL> alter table tbl move compress
  2  /
Table altered.
SQL> select bytes
  2  from user_segments
  3  where segment_name = 'TBL'
  4  /
     BYTES
   2097152
SQL> SY.