Oracle7 Server Administrator's Guide

Dropping Online Redo Log Groups

In some cases, you might want to drop an entire group of online redo log members. For example, you might want to reduce the number of groups in an instance's online redo log.

To drop an online redo log group, you must have the ALTER DATABASE system privilege.

Before dropping an online redo log group, consider the following restrictions and precautions:

An instance requires at least two groups of online redo log files, regardless of the number of members in the groups. (A group is one or more members.)

You can drop an online redo log group only if it is not the active group. If you need to drop the active group, first force a log switch to occur; see "Forcing A Log Switch" .

Make sure an online redo log group is archived (if archiving is enabled) before dropping it. To see whether this has happened, use the Server Manager ARCHIVE LOG command with the LIST parameter.

Drop an online redo log group with either the Drop Logfile Group menu item of Server Manager, or the SQL command ALTER DATABASE with the DROP LOGFILE clause.

The following statement drops redo log group number 3:

ALTER DATABASE DROP LOGFILE GROUP 3;

When an online redo log group is dropped from the database, the operating system files are not deleted from disk. Rather, the control files of the associated database are updated to drop the members of the group from the database structure. After dropping an online redo log group, make sure that the drop completed successfully, and then use the appropriate operating system command to delete the dropped online redo log files.