Specifies whether to append to or overwrite (delete and recreate) the derby.log file when the Derby engine is started. The derby.log file is used to record errors and other information. This information can help you debug problems within a system.
You can set this property even if the file does not yet exist; Derby creates the file.
By default, the file is deleted and then re-created.
This property is static; if you change it while Derby is running, the change does not take effect until you reboot.