If your database has been normalized you'll have to deal with child table records. Ours is one of those created, initially, by a tool ( Visio I believe) and is very highly normalized.

All previous attempts to do significant purging ( for example to create a small version of the production database for development ) exceeded sql server's capability due to the high degree of normalization and constraints.

We do have a nightly data purge job, but it's limited to just a few tables.