Why is undo backed with redo for GTT

Hello

One of the benefits of global temporary tables (gtt) is that it does not generate as much redo as 'normal' tables (See also a paralell thread on c.d.o.s). However, ggt's do generate undo which is backed by redo. Now, I do understand why the undo is necessary, but I don't understand why this undo must be backed by redo. In case of a crash, only the structure of the gtt must be recovered, not its content. So, it seems to me, that there is nothing to be rolled back on the ggt, hence the undo generated for the ggt needs not be recovered.

What am I missing?

Thanks
Rene Nyffenegger

-- 
  no sig today