Question on 'BYTES' in dba_free_space

Question

I have 11gr2 db.
SQL> select sum(bytes)/1024/1024/1024 Gbytes_free
  2                 from  sys.dba_free_space
  3  where tablespace_name = 'AI_TS';
GBYTES_FREE
  29.328003
we have 29GB free for tablespace AI_TS
Let's see what those datafiles in the tablespace:
SQL> select sum(bytes)/1024/1024/1024 Gbytes_alloc,
  2                                sum(maxbytes)/1024/1024/1024 Gbytes_max        
  3                 from sys.dba_data_files
  4  where   tablespace_name= 'AI_TS';
GBYTES_ALLOC GBYTES_MAX
   63.839844  63.999969
We are alomst FULL!
Question , what the 'BYTES' in dba_free_space ABOUT?
THANKS!Edited by: msdba on Apr 11, 2013 4:36 PM

Answer 1

msdba wrote:
dpapde wrote:
bytes in dba_free_space means total free extents in the tablespace AI_TS. 29GB may or may not be contiguous extents
whereas
bytes in dba_data_files means size of file in bytes which is 63G
and
maxbytes in dba_data_files is max file size which is also 63G in case of AI_TS tablespace.I think the "wall" -- sun(maxbtes) as shown in the dba_data_files.
we are very close to the wall.
we should waste no time to increase the quota of maxsiize if data file or adding a datafile.
Let me if i took it wrong.Just remember that BYTES in DBA_DATA_FILES is simply the size of the file.
When I'm checking to see if a tablespace needs more space, querying dba_tablespace_usage_metrics is quick and easy:
SQL> select * from dba_tablespace_usage_metrics;
TABLESPACE_NAME                USED_SPACE TABLESPACE_SIZE USED_PERCENT
JUSTIN                                128          383710   .033358526
SYSAUX                             155544          534750    29.087237
SYSTEM                              94240          468190   20.1285803
TEMP                                    0          385247            0
UNDOTBS1                              160          384991   .041559413
USERS                                2984           16640   17.9326923I'll then use a query to see how data files are allocated and configured in the tablespace, and make any adjustments that are necessary.
column file_name format a60
set linesize 150
select t.tablespace_name, d.file_name, d.bytes/1024/1024 file_mb, d.maxbytes/1024/1024 max_file_mb,
d.autoextensible, ((d.increment_by*t.block_size)/1024/1024) increment_mb
from dba_data_files d, dba_tablespaces t
where d.tablespace_name = t.tablespace_name
and d.tablespace_name = '&tablespace';
Enter value for tablespace: JUSTIN
old   5: and d.tablespace_name = '&tablespace'
new   5: and d.tablespace_name = 'JUSTIN'
TABLESPACE_NAME                FILE_NAME                                                       FILE_MB MAX_FILE_MB AUT INCREMENT_MB
JUSTIN                         /u01/app/oracle/oradata/ORCL/datafile/o1_mf_justin_8mtx19z1_        100       10240 YES          100
                               .dbf