@Override
	DBFieldIterator keyIteratorBefore(Field startField, Field primaryKey) throws IOException {
		return new PrimaryKeyIterator(null, null, startField, primaryKey, false);
	}
Delete all primary records which have the current
index value (lastKey).
@see db.DBFieldIterator#delete()
Ghidra/Framework/DB/src/main/java/db/FieldIndexTable.java