DBComparator comparator = options.comparator();
UserComparator userComparator;
if (comparator != null) {
userComparator = new CustomUserComparator(comparator);
}else{
userComparator = new BytewiseComparator();
}
internalKeyComparator = new InternalKeyComparator(userComparator);
memTable = new MemTable(internalKeyComparator);
immutableMemTable = null;