The challenge
At work, Jerome needs to pull together the music files he needs—and fast. But he also likes to browse his music collection when he's not sure which tune to mix into his latest production.
Today, Jerome uses directories to store his files. He puts much time and effort in creating directories and storing his files accordingly. But whatever he does, his directory tree always represents one sorting scheme. If he wants to collect files with different properties across directories, he cannot do that efficiently.