Reclaim free space in datafiles

Question

Hello:
I have taken over management of one of our test servers with Oracle 9i on Windows2000 and have noticed that there are two files that are much larger than the space that is actually being used:
D:\ORACLE\ORADATA\ORCL\SYSTEM01.DBF - 17964M - (Used 1,542M)
D:\ORACLE\ORADATA\ORCL\DATA01.DBF - 12511M - (Used 243M)
How can I reclaim all of this unused space?

Answer 1

Remember it is always best to reclaim space by moving all the objects to another tablespace and reclaiming all space. This will free up space within the tables and indexes as well.
I use the following script to generate the commands for me:
resizea.sql:
drop table alan99;
set pages 50
create table alan99 as
select max(block_id+blocks) block_id,file_id from dba_extents
group by file_id;
column tablespace_name format a15
column pct format 999.99
set wrap off
set lines 120
set trunc off
column file_id format 999
spool resizea.lst
select b.bytes/1024/1024-a.bytes/1024/1024 CURRENT_meg,
a.file_id,a.tablespace_Name,'alter database datafile '''||b.file_name||''' resize '
||trunc(c.block_id*8192/1024/1024+1)||'m;'
from dba_free_space a,dba_data_files b, alan99 c
where a.file_id=b.file_id
and a.block_id=c.block_id and a.file_id=c.file_id
order by current_meg;
set termout off
drop table alan99;
set termout on
spool off
select 'Your output has been saved as resizea.lst' from dual;
A script that will tell you what is inside is:
column owner format a30
column object format a30
set lines 120
set wrap off
set trunc off
set pages 50
set feedback on
column file_id format 999
select     /*+ Rule */     'free space' owner     /*"owner" of free space*/
,          ' ' object          /*blank object name*/
,          file_id                    /*file id for the extent header*/
,          block_id               /*block id for the extent header*/
,          blocks                    /*length of the extent, in blocks*/
from          dba_free_space
where          file_id=&1
union
select     /*+ Rule */ substr(owner,1,20)||' '||substr(segment_type,1,9) /*owner name (first 20 chars)*/
,          substr(segment_name,1,32)||'.'||partition_name     /*segment name*/
,          file_id                    /*file id for the extent header*/
,          block_id               /*block id for the extent header*/
,          blocks                    /*length of the extent, in blocks*/
from           dba_extents
where          file_id=&1
order by     3,4
/