I remember seeing this in the docs --

http://www.template-toolkit.org/docs/plain/FAQ/FAQ.html#Can_I_serve_templates_from_a_database_

Unfortunately the answer is a reference to "the mailing list" archives but not a link. Oh, it does say to subclass Tempalte::Provider.

There are multiple mailing lists and they don't seem to be indexed. A google search on site:template-toolkit.org didn't turn up anything useful. Oh well. The other answers in this thread probably suffice, but it would be nice to see this upstreamed into the TT2 docs.