public DBFieldIterator fieldKeyIterator(Field startKey) throws IOException {
		synchronized (db) {
			if (schema.useLongKeyNodes()) {
				throw new AssertException();
			}
			return new FieldKeyIterator(null, null, startKey);
		}
	}
Iterate over the primary keys in ascending sorted order
starting at the specified startKey.
@param startKey the first primary key.  If null the minimum key value will be assumed.
@return Field type key iterator
@throws IOException if an I/O error occurs.
Ghidra/Framework/DB/src/main/java/db/Table.java