MCOL-5021 adds support for an auxilliary (AUX) column in ColumnStore which improves the performance of the DELETE operation (refer to that ticket for more details). The AUX column, however, is only created when the user creates a new table in the ColumnStore version which supports this feature. This means the existing tables will not benefit from MCOL-5021. The objective of this ticket is to allow the user to add the AUX column to an existing table. One way to achieve this would be to create a new UDF that creates the AUX column.
While adding the new AUX column, the implementation needs to take into account existing deleted rows for the table.