It seems off-topic to me. There's no Perl focus in it that I can see. All the other nodes in the Database Programming section are about methods of accessing a database from Perl and doing something with the data.
It may be more appropriate in the Other Topics section, which has "Topics which aren't really about Perl, but which are of interest to the Perl programmer." (Though if it is in scope for inclusion, then so are most other SQL tutorials.)
And the good Perl-specific Database Design tutorials are... ? where?
Perhaps it doesn't mention Perl specifically, but IMHO, good Database Design principles are language-independent. And if "Database Design" doesn't belong in (or very near) "Database Programming," then I don't know why jdporter worked so very hard to categorize Tutorials.