Want to reduce the size of database

Question

Hi Guys,
We have Oracle 10G database over Unix platform, Customer want to reduce the size of database as much as possible and the ami of customer to move the storage area of this database to other one. so we resize some datafiles and get lots of free space at mount point but while checking the utilzation of table is showing somw what different as other . kindly the below O/P:
                                                                                    %                         MaxPoss    Max
Tablespace Name                         KBytes            Used            Free   Used         Largest          Kbytes   Used
*a DATA                             45,875,200       8,740,992      37,134,208   19.1       1,728,512     100,663,248   45.6
*a HIGH_S_DATA                      21,504,000       1,331,520      20,172,480    6.2       3,048,704               0     .0
*a HIGH_S_IND                       15,360,000         853,568      14,506,432    5.6       1,661,504               0     .0
*a IND_DATA                         57,241,600       3,512,832      53,728,768    6.1       3,995,648     100,663,248   56.9
*a LOW_S_DATA                      357,376,000      28,436,736     328,939,264    8.0       4,063,232     167,772,080  213.0
*a LOW_S_IND                       268,902,400      12,148,352     256,754,048    4.5       4,063,232      67,108,832  400.7
*a SYSAUX                            1,433,600         897,152         536,448   62.6         485,312      33,554,416    4.3
*a UNPARSED_DATA                       102,400             128         102,272     .1         102,272               0     .0
*a USERS                             4,096,000              64       4,095,936     .0       4,063,232      33,554,416   12.2
*m SYSTEM                            1,433,600         835,520         598,080   58.3         597,952      33,554,416    4.3
*m TEMP                             54,033,408      54,033,408               0  100.0               0      33,554,416  161.0
*m UNDOTBS1                         37,650,416         426,416      37,224,000    1.1       4,063,232      33,554,416  112.2
sum                                865,008,624     111,216,688     753,791,936
SQL> select sum(bytes/1024/1024/1024) from dba_segments;
SUM(BYTES/1024/1024/1024)
               54.5392456
SQL> select sum(bytes/1024/1024/1024) from dba_data_files;
SUM(BYTES/1024/1024/1024)
               773.406235above all o/p is different, no able to understand it. please help me in this .
Could you please tell me is there any way to reset the HWM at Datafile level and how we reset the HWM of those tables having Materlized view?

Answer 1

Hello,
I'm not really sure what is the problem here? Everything seems to be OK. From what I have seen ,your database can stand to be resized down quite a bit.
The actual amount it can be resized down depends on the highet HWM for the segments in the datafile, as in:
set line 200col file_name format a90
select file_name,
ceil( (nvl(hwm,1)*&&blksize)/1024/1024 ) USED_SPACE,
ceil( blocks*&&blksize/1024/1024) SIZE,
ceil( blocks*&&blksize/1024/1024) -
ceil( (nvl(hwm,1)*&&blksize)/1024/1024 ) ECONOMY --how much of the space can be reclaimed
from dba_data_files a,
( select file_id, max(block_id+blocks-1) hwm -- here we get the max hwm for the datafile from the extents residing within it
from dba_extents
group by file_id ) b
where a.file_id = b.file_id(+)
and ceil( blocks*&&blksize/1024/1024) -
ceil( (nvl(hwm,1)*&&blksize)/1024/1024 ) > 2000
>
You can also do a reorganization of the segment you suspect has a high degree of reclaimable space within its extents (high HWM and low actual space used). You can run segment advisor to help with that.
Hope it helps,