Repair the RPM database Revision as of Monday, 21 December 2015 at 02:30 UTC

I had a problem with running a yum update on some package. The process
would sleep indefinitely. A clue that something was wrong with the RPM
database (at /var/lib/rpm) was that running rpm -qa would hang as
well.

The solution is to rebuild the RPM database. In short:

 # Backups!
 tar -czvf /tmp/rpm.tgz /var/lib/rpm
 
 # Remove the database locks
 rm -f /var/lib/rpm/__db*
 
 # Rebuild!
 rpm -vv --rebuilddb

That should do it.