[Dovecot] Sieve and UserDB/SQL support

[ben]

Hi,

I would like to know if plugins of sieve support UserDB/SQL backend.
For example, for the vacation plugin, is it possible to retrieve a 
field like "sieve_vacation_days", "sieve_vacation_reason", and so on.. 
on user_query?

Or, there is a plan for implement this?

Thanks

------
dovecot version: 2.0.13