Personally, I do not think it would be a good idea to have an RDBMS which is entirely Perl and open to the user. It would have to re-invent too many wheels and would not really add much to the core of the DB-engine. Yes, you could use our beloved Perl to speak to the DB-engine, but what extras would that give since you can already speak to the DB-engine through DBI/DBD and SQL? I am in no need of a Perly SQL, since SQL suits me rather good for what it is intended to do.