Needs Clarification Regarding Segments and Datafiles

Question

Hi,
I want clarification regarding Segments, Datafiles and extents.
As we know that A segment is made of one or more extents and extents are composed of one or more datablocks in the HD.
Since all data are store in Datafiles which are composed of extents and datablocks. I want to know weather a table(Segment) can span to multiple datafiles or in a sigle datafile.
Regards,
D.Abbasi

Answer 1

And an easy way to check it by yourself :
SQL> create tablespace abbasi_tbs
  2  datafile 'E:\ORADATA\DEMO111P\abbasi_01.dbf' size 1m autoextend off,
  3           'E:\ORADATA\DEMO111P\abbasi_02.dbf' size 1m autoextend off;
Tablespace created.
SQL> create table abbasi_tbl (id number)
  2  tablespace abbasi_tbs;
Table created.
SQL> insert into abbasi_tbl
  2  select rownum as rn
  3  from   dual
  4  connect by level <=10000;
10000 rows created.
SQL> commit;
Commit complete.
SQL> select distinct file_id
  2  from   dba_extents
  3  where  segment_name ='ABBASI_TBL';
   FILE_ID
         6
         7
or...
SQL> select distinct DBMS_ROWID.ROWID_RELATIVE_FNO(rowid)
  2  from   abbasi_tbl;
DBMS_ROWID.ROWID_RELATIVE_FNO(ROWID)
                                   6
                                   7
SQL> select file_name from dba_data_files where file_id in (6,7);
FILE_NAME
E:\ORADATA\DEMO111P\ABBASI_01.DBF
E:\ORADATA\DEMO111P\ABBASI_02.DBF
SQL>Nicolas.
added the ROWID function usage
Edited by: N. Gasparotto on Jun 21, 2009 11:02 AM