primitive types have default values, (e.g. boolean, int, ...) but primative wrapper classes do not and can be null (e.g. Boolean, Integer, ...)

create table wal {
  id timeuuid,
  follows timeuuid,
  read <Counting Quotient Filter, Set<{keyspace, col, schema generation, timestamp}>>
  write <Counting Quotient Filter, Set<{keyspace, col, schema generation, timestamp}>>
  primary key (id, follows)
}
begin:
  - insert into wal (timeuuid, parent timeuuid,



        // NOTE: Update operations have no meaning when they only contain primary key components, so
        // given that `properties` is ordered with the keys first if we find that the last element
        // is either a partition key or clustering column then we know we should just skip this operation.
        ColumnType ct = ((HelenusProperty) properties.toArray()[properties.size() - 1]).getColumnType();
        if (ct != ColumnType.PARTITION_KEY && ct != ColumnType.CLUSTERING_COLUMN) {
            return;
        }



	public Stream<E> sync() {
	    ListenableFuture<Stream<E>> future = async();
        Futures.addCallback(future, new FutureCallback<String>() {
            @Override
            public void onSuccess(String contents) {
                //...process web site contents
            }

            @Override
            public void onFailure(Throwable throwable) {
                log.error("Exception in task", throwable);
            }
        });
	}