reorg is useful when:
A large number of forwarded rows causes extra I/O during read operations.
Inserts and serializable reads are slow because they encounter pages with noncontiguous free space that must be reclaimed.
Large I/O operations are slow because of low cluster ratios for data and index pages.
sp_chgattribute was used to change a space management setting (reservepagegap, fillfactor, or exp_row_size) and the change is to be applied to all existing rows and pages in a table, not just to future updates.
