To see how full tablespaces are in an Oracle database, you might need to add a datafile.
If the used size of a tablespace is more than 80% of its maximum size, consider adding a datafile. The script recommends adding a datafile when the tablespace is 80% full.
Query return the result as :

Query to suggest which datafiles to add if they are 75% full.
Explain the following query columns :
| Name | Name of Tablespace |
| Maxsize(GB) | If autoextensible of datafile is on then it will pick sum of maxsize otherwise sum of bytes column. |
| Used(GB) | sum of bytes column of all datafiles |
| Free(GB) | space free in datafiles |
| USED% | check with used(GB) and free(GB) column — no n |
| Suggestion | Give suggesion on tablespace which space is utilized above 80% |
Script to check tablespace usage and suggest adding files to the database.
set colsep |
set linesize 200 pages 100 trimspool on numwidth 14
col name format a15
col owner format a15
col "Used(GB)" format a10
col "Free(GB)" format a10
col "(Used)%" format a10
col "Size(GB)" format a10
col "MaxSize(GB)" format a11
col "(Used)%" format a10
col Suggestion format a26
select Name,"MaxSize(GB)","Size(GB)","Used(GB)","Free(GB)","(Used)%",
Case when AcctoMaxSizeUsed >= 80 then 'NeedtoAddDatafile' else '' end as Suggestion
from
(
SELECT d.status "Status", d.tablespace_name as Name,
TO_CHAR(NVL(a.maxbytes / 1024 / 1024 /1024, 0),'999999.90') "MaxSize(GB)",
TO_CHAR(NVL(a.bytes / 1024 / 1024 /1024, 0),'999999.90') "Size(GB)",
TO_CHAR(NVL(a.bytes - NVL(f.bytes, 0), 0)/1024/1024 /1024,'999999.90') "Used(GB)",
TO_CHAR(NVL(f.bytes / 1024 / 1024 /1024, 0),'999999.90') "Free(GB)",
TO_CHAR(NVL((a.bytes - NVL(f.bytes, 0)) / a.bytes * 100, 0), '990.00') "(Used)%",
TO_CHAR(NVL( (NVL(a.bytes, 0)) / a.maxbytes * 100, 0), '990.00') as AcctoMaxSizeUsed
FROM sys.dba_tablespaces d,
(select tablespace_name, sum(bytes) bytes, SUM( CASE WHEN autoextensible = 'YES' THEN maxbytes ELSE bytes END ) as maxbytes from dba_data_files group by tablespace_name) a,
(select tablespace_name, sum(bytes) bytes from dba_free_space group by tablespace_name) f WHERE
d.tablespace_name = a.tablespace_name(+) AND d.tablespace_name = f.tablespace_name(+) AND NOT
(d.extent_management like 'LOCAL' AND d.contents like 'TEMPORARY')
UNION ALL
SELECT d.status
"Status", d.tablespace_name as Name,
TO_CHAR(NVL(a.maxbytes / 1024 / 1024 /1024, 0),'999999.90') "MaxSize(GB)",
TO_CHAR(NVL(a.bytes / 1024 / 1024 /1024, 0),'999999.90') "Size(GB)",
TO_CHAR(NVL(t.bytes,0)/1024/1024 /1024,'999999.90') "Used(GB)",
TO_CHAR(NVL((a.bytes -NVL(t.bytes, 0)) / 1024 / 1024 /1024, 0),'999999.90') "Free(GB)",
TO_CHAR(NVL(t.bytes / a.bytes * 100, 0), '990.00') "(Used)%" ,
TO_CHAR(NVL( NVL(a.bytes, 0) / a.maxbytes * 100, 0), '990.00') as AcctoMaxSizeUsed
FROM sys.dba_tablespaces d,
(select tablespace_name, sum(bytes) bytes,SUM( CASE WHEN autoextensible = 'YES' THEN maxbytes ELSE bytes END ) as maxbytes from dba_temp_files group by tablespace_name) a,
(select tablespace_name, sum(bytes_cached) bytes from v$temp_extent_pool group by tablespace_name) t
WHERE d.tablespace_name = a.tablespace_name(+) AND d.tablespace_name = t.tablespace_name(+) AND
d.extent_management like 'LOCAL' AND d.contents like 'TEMPORARY'
) k order by suggestion
After getting the recommendation of adding datafile in tablespace.
Check the datafiles present in the tablespace :
select file_name from dba_Data_Files where tablespace_name = 'TEST';
Or
set line 999 pages 999 col FILE_NAME format a50 col tablespace_name format a15 Select tablespace_name, file_name, autoextensible, bytes/1024/1024/1024 "USEDSPACE GB", maxbytes/1024/1024/1024 "MAXSIZE GB" from dba_data_files
If you need to add datafiles, use the following commands:
alter tablespace USERS add datafile 'D:\ORACLE11204\ORADATA\PEGA\USERS02.DBF' size 1G autoextend on next 500M maxsize 16G;


