How do I change the temporary directory that SQL Data Compare uses?
If SQL Data Compare causes you to run out of hard disk space, you may want to move SQL Data Compare’s temporary workspace to another drive or folder. To do this, go to the Control Panel, double-click System, then click the Advanced tab, and finally, Environment Variables. Create a new variable called RGTEMP and replace the path with the temporary folder you would like to use. In order for the change to take effect, you must log out of Windows and back in again. Note this setting will only affect other Red Gate programs.