Issues converting MyISAM table to InnoDB (auto column issue)
At present, only MyISAM permits auto_increment values in a composite key. I wrote about this over a year ago : How can you have two auto-incremental columns in one table?

According to the Book



Section 5.7 Page 89 Paragraph 1 states the following:


  The MyISAM Storage Engine supports composite indexes that include an AUTO_INCREMENT column. This allows the creation of independent sequences.


which I know you are well aware of. I simply stated this for the benefit of other readers.

As I stated in my past post


  This is not possible with InnoDB based on auto_increment columns being tied directly to the gen_clust_index (aka Clustered Index) !!!


Allowing this would require redesigning the gen_clust_index to accommodate such a mechanism.