I just converted several large tables from MyISAM to InnoDB. When I view the tables in phpMyAdmin, they are showing a significant amount of overhead (One table has 6.8GB). Optimizing the tables (which isn't a supported command on InnoDB) has no affect like it does on MyISAM. Is this a result of InnoDB having the ever growing data file that never returns space even after deletes? If that's the case, I've never seen overhead like this before from other InnoDB tables. Is there a way to clean this up? Edit: Here are the things I've tried (with no success): Optimize Table Reorder table by primary key Defragment table