Resizing initial extent

Question

HI Guys
Is there a way to resize the initial extent of a table without dropping and recreating by changing the INITIAL parameter? Is there a kind of package or something available?
We have lot of tables with initial size is quite big as they were defined in production. Unable to change the initial parameter when the tables are imported from prod. The dump is exported with COMPRESS=N and ROWS=N.
Appreciate your help.
Regards
Bhaskara

Answer 1

There is no way to redefine the initial extent but by dropping/recreating it. But you can try to deallocate the unused space beyond the High Water Mark (alter table table_name deallocate unused keep 0;), as shown on the next demo:
SQL> edit
Wrote file afiedt.buf
  1  create table emp1
  2  storage( initial 8m next 8m )
  3* as select * from employees
SQL> /
Table created.
SQL> analyze table emp1 compute statistics;
Table analyzed.
SQL>  select blocks, table_name from user_tables;
    BLOCKS TABLE_NAME
         6 EMP1
SQL> r
  1  select blocks, segment_name from user_segments
  2* where segment_name ='EMP1'
    BLOCKS SEGMENT_NAME
      1024 EMP1
SQL> alter table emp1 deallocate unused keep 0;
Table altered.
SQL> select blocks, segment_name from user_segments
  2  where segment_name ='EMP1';
    BLOCKS SEGMENT_NAME
         8 EMP1
SQL> select table_name, initial_extent from user_tables;
TABLE_NAME                     INITIAL_EXTENT
EMP1                                    65536
EMPLOYEES                               65536~ Madrid