Enables IQ message log file wrapping, and sets maximum size of this file.
Integer between 0 and 2047, in MB
Can only be set for the PUBLIC group. Requires DBA privileges to set. Takes effect immediately.
0 (message log wrapping disabled)
When you start a database, messages are recorded in the IQMSG log file, and each new line is appended to the end of the file.
Initially, message log wrapping is disabled (IQMSG_LENGTH_MB is 0), messages are always appended to the end of the file, and the file continues to grow.
When message log wrapping is enabled (IQMSG_LENGTH_MB is greater than 0), the IQMSG log file can only grow to the specified size. The maximum size you can specify is 2047 (2GB). When it reaches that size, new messages are written to the beginning of the file, overwriting existing messages on a line-by-line basis.
If wrapping is enabled when the database is shut down, it is still enabled the next time the database is started. If you then disable wrapping, by setting IQMSG_LENGTH_MB = 0, Sybase IQ writes new messages continuously to the ending position of the most recent message, overwriting any existing messages, until it reaches the end of the file. From then on, it appends new messages to the end of the file.
When wrapping is enabled, three tags remind you that the last message in the file may not be the most recent message, and help you identify where new messages are being placed.
This tag indicates the ending position of the most recent message:
<next msg insertion place>
This tag occurs at the start of the file:
!!!!!! log wrapped back here from the end of the file !!!!!!
This tag occurs at the end of the file:
!!!!!! log wrapped back to the beginning of the file !!!!!!
If a database file already exists and its IQMSG file is larger than IQMSG_LENGTH_MB, the maximum file size is the actual file size. Setting this option does not truncate the file.
