datachange has the following restrictions:
datachange statistics are not maintained on tables in system tempdbs, user-defined tempdbs, system tables, or proxy tables.
datachange updates are non-transactional. If you roll back a transaction, the datachange values are not rolled back, and these values can become inaccurate.
If memory allocation for column-level counters fails, the SAP ASE server tracks partition-level datachange values instead of column-level values.
If the SAP ASE server does not maintain column-level datachange values, it then resets the partition-level datachange values whenever the datachange values for a column are reset.