I'm planning on writing a rather simple Wiki (actually, in its final implementation, it should be a base from which it would be trivial to create a wiki or a blog) in perl, but I don't much feel up to making my own database.

What I need is a very small, lightweight database, and I wondered what advice I could get.

Thanks.

I would think that MySQL would be a perfect database to do this with.

Software development these days is all about component reuse, unless you want to learn how to implement a database for practice or fun I suggest use MySQL or other free DBs.
Look for my website in my signature, it's a wiki I implemented with JSP/Servlet and MySQL. Have fun with your development :-)

you might want to check on CPAN that you aren't duplicating somebody's work -- CGI::Kwiki sounds like what you are planning to build, and I think there are one or two others mentioned in the kwiki docs or web pages. If you still want to go ahead on your own, you should check out how they do things. There is usually some effort made to make the project not be specific to just one database through the use of "plugins."

DBI should make access to mysql, postgresql, and perhaps sqllite and some other sql databases roughly equivalent (at least for simple operations)

oh yeah, for rolling your own database you might find that the filesystem works pretty well -- this is what kwiki does by default. You can perform "queries" with grep