- Arun Kumar
Datafile utilization check
When you want to shrink a datafile, you must always check the single datafile utilization. In case if you shrink datafile more than the used size, it will fail. Below query gives the datafile utilization and depending upon the datafile free space, you can shrink it
Query to check free space in data file
col file_name for a60;
set pagesize 500;
set linesize 500;
SELECT SUBSTR (df.NAME, 1, 40) file_name, df.bytes / 1024 / 1024 allocated_mb,
((df.bytes / 1024 / 1024) - NVL (SUM (dfs.bytes) / 1024 / 1024, 0))
used_mb,
NVL (SUM (dfs.bytes) / 1024 / 1024, 0) free_space_mb
FROM v$datafile df, dba_free_space dfs
WHERE df.file# = dfs.file_id(+)
GROUP BY dfs.file_id, df.NAME, df.file#, df.bytes
ORDER BY file_name;
Query to find % free in each data file
This query gives usage of datafile, percentage free in the datafile. Query can be used to find datafiles which are not in use and can be resized looking into the free percentage.
SET PAGESIZE 60
SET LINESIZE 900
COLUMN "Tablespace Name" FORMAT A10
COLUMN "File Name" FORMAT A40
SELECT Substr(df.tablespace_name,1,20) "Tablespace Name",
Substr(df.file_name,1,80) "File Name",
Round(df.bytes/1024/1024,0) "Size (M)",
decode(e.used_bytes,NULL,0,Round(e.used_bytes/1024/1024,0)) "Used (M)",
decode(f.free_bytes,NULL,0,Round(f.free_bytes/1024/1024,0)) "Free (M)",
decode(e.used_bytes,NULL,0,Round((e.used_bytes/df.bytes)*100,0)) "% Used"
FROM DBA_DATA_FILES DF,
(SELECT file_id,
sum(bytes) used_bytes
FROM dba_extents
GROUP by file_id) E,
(SELECT sum(bytes) free_bytes,
file_id
FROM dba_free_space
GROUP BY file_id) f
WHERE e.file_id (+) = df.file_id
AND df.file_id = f.file_id (+)
ORDER BY df.tablespace_name,
df.file_name
/