OMG (ORACLE managed files)
……to create tablespaces without specifying data files location
- By introducing OMF from ORACLE 9i third party software need not maintain data file location anymore while creating the tablespace [OMF works regardless of what operating system behind]
- Simplifies the creation of database default values:
100 mb size
Auto-extend on
Locally managed TS
For data files 01_mf_%t_%u.dbf
for log files 01_mf_%g_%u.log
for control file 01_mf_%u.ctl
g group member
mf managed files
t tablespace name
u unique id [8 characters]
- OMF reduces the corruption caused by administrators specifying the wrong file.
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Problems with OMF
We can not have multiple destinations for the datafiles, wherein in the case of log files, we can have multiple destinations.
[more I/Os]
We need not to maintain including contents and data files when dropping tablespace.
DEMO ON OMF
Dba12 dbs]$ vi initrajpar.ora
SYS > sho parameter db_create_
SYS > create tablespace omf_1;
SYS> select file_name, tablespace_name from dba_data_files;
SYS> select file_name, bytes, tablespace_name from dba_data_files;
SYS> create tablespace omf_2 datafile size 20m;
SYS > create tablespace omf_3 extent management dictionary; [default local]
SYS > alter database add logfile group 3 size 4m;
[size 4m compulsory, else default is 100m]
Database creation
Dba12 ~] $ export ORACLE _ SID = rajpar2
Dba12~] $ cd $ ORACLE_HOME/dbs
Dba12 dbs]$ cp init. Ora initrajpar2.ora
Dba12 dbs]$ vi intrajpar2. Ora
Db_name=rajpal2
Instance_name=rajpar2
Db_create_file_dest=’/disk4/oradata/pal2’
User_dump_dest=’disk4/oradata/pal2/udump’
Background_dump_dest=’/disk4/oradata/pal2/bdump’
Core_dump_dest= ‘/disk4/oradata/pal2/cdump’
# undo_tablespace=undotbs
:wq
Dba12 dbs] $cd
Dba12 ~[$ sqlplus ‘/as sysdba’
SQL > startup nomount
SQL> create database rajpal2;
For an in-depth knowledge, click on below
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