Serializing a tree and storing it in a BLOB (Binary Large OBject) field is a lot faster than decomposing the tree into separate nodes and storing each (and then having to issue a bunch of SELECTs to reconstitute the tree).

If you're using MySQL and Perl, portability shouldn't be an issue. The only issue is which method you use to serialize objects. See storing serialized object in a database for an earlier discussion of alternatives.