RPM database gone

[dirk calvyn puk ac za]

I've just tried to upgrade my system from RedHat 5.2 to 6.0.
I was told that my /usr had too little space, and tried to
abort installation so I could free up some space.  There is 
no elegant way to do so from the installation menu.  
I now know that one should type Ctrl-Z and kill the install 
process from the command line.  Instead, I did the three-finger 
salute, which on a running system works just fine, decent shutdown 
etc, but on the install system just makes it disappear like DOS.  

Problems on rebooting: file systems needed checking, no sweat,
but the RPM database is gone.  Not RPMsaved, nothing.  Can it
really be true that there is no copy of it, anywhere?  Is there
no way to get it back?

Dirk