Adaptive Server 15.7 SP100 includes a new parameter—defrag—for the reorg command that lets you schedule and resume reorganization, and allows concurrent reads or writes on the data being reorganized.
reorg defrag locks each row or page, as per the locking scheme of the object, and begins and commits a transaction for every data chunk that is processed. The data reorganization space requirement does not exceed the size of an allocation unit (256 data pages). Index updates for reorganized data do not consume extra space. For every data partition undergoing incremental reorganization, a row is stored in sysattributes.