Redo Log Files

Redo Log Files

 The Oracle server needs a minimum of two online redo log file groups
 The maximum and default value for MAXLOGMEMBERS, MAXLOGFILES is dependent on your operating system.
 The minimum size of an online redo log file is 50 KB.


Adding new group:

ALTER DATABASE ADD LOGFILE GROUP 4
('C:\oracle\product\10.1.0\oradata\bank\REDO04a.rdo',
'C:\oracle\product\10.1.0\oradata\bank\REDO04b.rdo')
SIZE 10M;

Adding a member in a group:

ALTER DATABASE ADD LOGFILE MEMBER
'C:\oracle\product\10.1.0\oradata\bank\REDO01a.rdo','C:\oracle\product\10.1.0\oradata\bank\REDO01b.rdo' TO GROUP 1,
'C:\oracle\product\10.1.0\oradata\bank\REDO02a.rdo' TO GROUP 2,
'C:\oracle\product\10.1.0\oradata\bank\REDO03a.rdo' TO GROUP 3;

Dropping a Redo Log Group

ALTER DATABASE DROP LOGFILE GROUP 3;

• An instance requires at least two groups of online redo log files.
• An active or current group cannot be dropped.
• When an online redo log group is dropped, the operating system files are not deleted.


Dropping Online Redo Log Members

ALTER DATABASE DROP LOGFILE MEMBER 'C:\oracle\product\10.1.0\oradata\bank\REDO03a.rdo';

• If the member you want to drop is the last valid member of the group, you cannot drop
that member.
• If the group is current, you must force a log file switch before you can drop the
member.
• If the database is running in ARCHIVELOG mode and the log file group to which the
member belongs is not archived, then the member cannot be dropped.
• When an online redo log member is dropped, the operating system file is not deleted.