phpFlickr Caching to Filesystem or MySQL?

Are you supposed to be able to see distinct filenames via phpFlickr's caching to filesystem or MySQL? I've set the parameters as listed in the readme, but caching does not seem to generate any files or mysql table rows.

I've tried both the filesystem (chmod 777 in cache folder) and mysql method (manually created cache table). Any advice on what's to be done to e开发者_运维知识库nable caching on phpFlickr ? http://phpflickr.com/docs/caching/

$f = new phpFlickr($key);

$f->enableCache("db", "mysql://user:password@localhost/database");