dovecot - May 2017 - virtual folder: how to store in mysql?

Hello Community,

Now that virtual folders seem to work fine, I stil lhave 2 questions :

1? Is it possible to store the virtual folder definition (aka content of 
Folder/dovecot-virtual) in mysql?

2? I have duplicates in my "Unseen", which both correctly disappear
once
handled one of them
Example:
!Inbox
*
-Inbox (tried this but does not succeed
-Trash
-Trash/*
Public/*
     Unseen

2?bis :) I tried to put the "common defs" in a shared folder 
(/etc/dovecot/virtual) using personal index
location = 
virtual:/etc/dovecot/virtual:INDEX=/sd/MAIL_IMAP_POP/%d/%n/__Virtual/
This does not work, I have to *copy* (even symlinks do not succeed) the 
definitions and use
location = 
virtual:/sd/MAIL_IMAP_POP/%d/%n/__Virtual:INDEX=/sd/MAIL_IMAP_POP/%d/%n/__Virtual/
I already tried to set perms on /etc/dovecot/virtual to: vmail.vmail 
rw(x)------

Thank you!

Cheers