It sounds like the Windows registry is an ad hoc, informally-specified, bug-ridden, slow implementation of half of a filesystem. (Amazing how Greenspun's Tenth Rule can be slightly adapted and apply to so many different situations)
If you should find yourself creating an ad hoc, informally-specified, bug-ridden, slow implementation of half of X, stop! Throw it away and use X instead. You'll save yourself and everyone who has to interact with your system a whole lot of grief.
And since a filesystem is an ad hoc, informally-specified (or unspecified, how long did it take before linux could read ntfs?), slow (for some things: no indexes), bug-ridden (FAT 8.3 name limit, limited metadata such as file types), implementation of a database...
But filesystems have been in use long enough that most bugs have been fixed or worked around in the tools. And of course the guys who invented the 'filesystem' didn't have any databases to use instead.
Some would argue that X is an ad-hoc, informally-specified, bug ridden, slow implementation of half a window system. The specifications are pretty clear, even if some are honoured more in the breach than in the observance, but otherwise they'd be right. ("This is not a bug; this is a design decision.")
If you should find yourself creating an ad hoc, informally-specified, bug-ridden, slow implementation of half of X, stop! Throw it away and use X instead. You'll save yourself and everyone who has to interact with your system a whole lot of grief.