Changing the Database-Logging Mode

You can use ondblog, ontape, or ISA to add or change logging. Then use ON–Bar, or ontape to back up the data. When you use ON–Bar or ontape, the database server must be in online, single-user, or quiescent mode.

For information on ON–Bar and ontape, see the IBM Informix Backup and Restore Guide.

Table 35 shows how the database server administrator can change the database-logging mode. Certain logging mode changes take place immediately, while other changes require a level-0 backup.

Some general points about changing the database-logging mode follow:

• While the logging status is being changed, the database server places an exclusive lock on the database to prevent other users from accessing the database, and frees the lock when the change is complete.
• If a failure occurs during a logging-mode change, check the logging mode in ISA or the flags in the sysdatabases table in the sysmaster database, after you restore the database server data. For more information, see Monitoring the Logging Mode of a Database. Then retry the logging-mode change.
• After you choose either buffered or unbuffered logging, an application can use the SQL statement SET LOG to change from one logging mode to the other. This change lasts for the duration of the session. For information on SET LOG, see the IBM Informix Guide to SQL: Syntax.
• If you add logging to a database, the change is not complete until the next level-0 backup of all the storage spaces for the database.