How To Shrink Tablespaces

How To Shrink Tablespaces

select file_name, ceil( (nvl(hwm,1)*&&blksize)/1024/1024/1024 ) resize_GB, ceil( blocks*&&blksize/1024/1024/1024) currsize, ceil( blocks*&&blksize/1024/1024/1024) - ceil( (nvl(hwm,1)*&&blksize)/1024/1024/1024 ) reclaimable_GB from dba_data_files a, ( select file_id, max(block_id+blocks-1) hwm from dba_extents group by file_id ) b where a.file_id = b.file_id(+)
/

---With alter command individual tablespace.

select file_name,'alter database datafile'||' '''||file_name||''''||' resize '||ceil( (nvl(hwm,1)*&&blksize)/1024/1024/1024 )||''||'G'||';', ceil( (nvl(hwm,1)*&&blksize)/1024/1024/1024 ) resize_GB, ceil( blocks*&&blksize/1024/1024/1024) currsize, ceil( blocks*&&blksize/1024/1024/1024) - ceil( (nvl(hwm,1)*&&blksize)/1024/1024/1024 ) reclaimable_GB from dba_data_files a, ( select file_id, max(block_id+blocks-1) hwm from dba_extents group by file_id ) b where a.file_id = b.file_id(+) and a.tablespace_name='SYSTEM' and ceil( blocks*&&blksize/1024/1024/1024) - ceil( (nvl(hwm,1)*&&blksize)/1024/1024/1024 )!=0 order by 5 desc /

---with alter command.

set linesize 1000 pagesize 0 feedback off trimspool on
with
hwm as (
-- get highest block id from each datafiles ( from x$ktfbue as we don't need all joins from dba_extents )
select /*+ materialize */ ktfbuesegtsn ts#,ktfbuefno relative_fno,max(ktfbuebno+ktfbueblks-1) hwm_blocks
from sys.x$ktfbue group by ktfbuefno,ktfbuesegtsn
),
hwmts as (
-- join ts# with tablespace_name
select name tablespace_name,relative_fno,hwm_blocks
from hwm join v$tablespace using(ts#)
),
hwmdf as (
-- join with datafiles, put 5M minimum for datafiles with no extents
select file_name,nvl(hwm_blocks*(bytes/blocks),5*1024*1024) hwm_bytes,bytes,autoextensible,maxbytes from hwmts right join dba_data_files using(tablespace_name,relative_fno)
)
select case when autoextensible='YES' and maxbytes>=bytes then -- we generate resize statements only if autoextensible can grow back to current size '/* reclaim '||to_char(ceil((bytes-hwm_bytes)/1024/1024),999999) ||'M from '||to_char(ceil(bytes/1024/1024),999999)||'M */ ' ||'alter database datafile '''||file_name||''' resize '||ceil(hwm_bytes/1024/1024)||'M;' else -- generate only a comment when autoextensible is off '/* reclaim '||to_char(ceil((bytes-hwm_bytes)/1024/1024),999999)
||'M from '||to_char(ceil(bytes/1024/1024),999999) ||'M after setting autoextensible maxsize higher than current size for file ' || file_name||' */' end SQL from hwmdf where bytes-hwm_bytes>1024*1024 -- resize only if at least 1MB can be reclaimed order by bytes-hwm_bytes desc
/

---with alter command in GB

set linesize 1000 pagesize 0 feedback off trimspool on
with
hwm as (
-- get highest block id from each datafiles ( from x$ktfbue as we don't need all joins from dba_extents )
select /*+ materialize */ ktfbuesegtsn ts#,ktfbuefno relative_fno,max(ktfbuebno+ktfbueblks-1) hwm_blocks
from sys.x$ktfbue group by ktfbuefno,ktfbuesegtsn
),
hwmts as (
-- join ts# with tablespace_name
select name tablespace_name,relative_fno,hwm_blocks
from hwm join v$tablespace using(ts#)
),
hwmdf as (
-- join with datafiles, put 5GB minimum for datafiles with no extents
select file_name,nvl(hwm_blocks*(bytes/blocks),5*1024*1024*1024) hwm_bytes,bytes,autoextensible,maxbytes
from hwmts right join dba_data_files using(tablespace_name,relative_fno)
)
select
case when autoextensible='YES' and maxbytes>=bytes
then -- we generate resize statements only if autoextensible can grow back to current size
'/* reclaim '||to_char(ceil((bytes-hwm_bytes)/1024/1024/1024),999999)
||'GB from '||to_char(ceil(bytes/1024/1024/1024),999999)||'GB */ '
||'alter database datafile '''||file_name||''' resize '||ceil(hwm_bytes/1024/1024/1024)||'GB;'
else -- generate only a comment when autoextensible is off
'/* reclaim '||to_char(ceil((bytes-hwm_bytes)/1024/1024/1024),999999)
||'GB from '||to_char(ceil(bytes/1024/1024/1024),999999)
||'GB after setting autoextensible maxsize higher than current size for file '
|| file_name||' */'
end SQL from hwmdf where bytes-hwm_bytes>1024*1024*1024 -- resize only if at least 1GB can be reclaimed order by bytes-hwm_bytes desc
/