Kristian,
 
> What do you think about the below patch?
> It puts the cached_charset into the THD, which seems to be a better place,
> since it describes which charset is currently active in the THD.
 
>(I also introduced THD::system_thread_info, as I did not want to add even more
data to the THD, which is already far too big; that's why the patch is a bit
bigger).
 
It seems most reasonable to put cached_charset into the THD, and your patch is
very smart and clean.
 
Thanks!