[ADMIN] turn off auto index for foreign key

[Tommy Cheng]

Hi admins,
  I would like to turn off the auto index for child table's foreign key. It
is because i want to read the information_schema for table, column, index,
unique and so on after creating the database. How to turn off the auto
behavior? Or Is there a way to distinguish between auto one and user created
index?
  Thanks
Tommy Cheng