dovecot - Nov 2014 - Shared mailboxes using SQL

I recently tried to change from the simple file to a SQL dictionary for 
ACL.  While the Wiki instructions seemed fairly clear I was having 
errors.  After some further digging, and a little thinking - I read the 
errors and tried to infer what was happening.

I have some IMAP groups configured for sharing.  And I guessed the 
example dictionary didn't allow for them.  Looking at my existing 
shared-mailboxes.db flat file I saw something that gave me a clue. So I 
added the following:

map {
   pattern = shared/shared-boxes/group/$to/$from
   table = user_shares
   value_field = dummy

   fields {
     from_user = $from
     to_user = $to
   }
}

And things started working again!  A suggestion that perhaps this be 
added to the wiki - possibly with a bit more information on the "map" 
sections.

Also - would there be any benefit to setting up a separate SQL table for 
groups?

-- 
Daniel