Hi Alexey,
Thanks for this answer.
Sorry for this question but I had no informations about the status of this release (beginning, advanced state ...), this was the purpose of my question also because the non blocking DDL feature is quite important for us, it's even very very important as if it's needed to wait some months maybe the choice of Galera/PXDBC will be questioned at our company level and it could be possible that a new search of another solution to be studied ...
We will wait for the moment !
Regards,
Laurent