Message Log File Management

By default, the message log file grows to an unlimited size, and exists until you drop the database. To control the size of the message log file, you can set a limit on the size of the file and enable either message log wrapping or log archiving.

You can delete, rename, or copy the message file at any time after stopping the database.

Message log management is controlled by either the server properties IQMsgMaxSize and IQMsgNumFiles, or the server startup switches -iqmsgsz and -iqmsgnum:

IQMsgMaxSize or -iqmsgsz sets an upper limit in megabytes (MB) on the active message log size. Allowed values are integers between 0 and 2047 (inclusive). The default is 0, which means there is no limit on the size of the message log file.
IQMsgNumFiles or -iqmsgnum sets the number of message log archives. Allowed values are integers between 0 and 64 (inclusive). The default is 0, which means that messages are wrapped in the main message log file and there is no archiving.

The value of the server property takes precedence over the corresponding server startup switch. When the server starts, the values of the -iqmsgsz and -iqmsgnum server switches are written in the server log file.

For information on setting the IQMsgMaxSize and the IQMsgNumFiles server properties, see Reference: Building Blocks, Procedures > System Procedures > sa_server_option system procedure.

For information on setting the -iqmsgsz and -iqmsgnum server startup switches, see Utility Guide > start_iq Database Server Startup Utility.

Note: The IQMSG_LENGTH_MB database option has been deprecated; remove it from existing scripts and code. Attempts to use IQMSG_LENGTH_MB return an error.

Message Log Wrapping
Message log wrapping overwrites existing messages at the beginning of the file with new messages upon reaching a maximum log size.
Message Log Archives
Message log archives limit file size while maintaining all of the information written to the message log file.
When to Back Up Message Log and Archives
Sybase recommends that you create backups for the message log file dbname.iqmsg and the message log archives, even though these files are not required for a restore.
Daylight Savings Time and Message Logs
If you run Sybase IQ in a country that observes Daylight Savings Time, reboot Sybase IQ servers after the change back to standard time.

Parent topic: Message Log Contents