Comment # 6 on bug 1095144 from Peter Varkoly

(In reply to Martin Willisegger from comment #0)
> Postfix 3.3 in Leap-15 does no longer support mysql virtual maps.
> 
> Installed is:
> i  | postfix            | A fast, secure, and flexible mailer
> i+ | postfix-mysql      | Postfix plugin to support MySQL maps
> 
> When I use this line in main.cf:
> virtual_mailbox_maps = mysql:/etc/postfix/mysql_virtual_mailbox_maps.cf
> 
> and restart postfix, or check postfix with postconf -n this ends up in this
> warn messages:
> 
> postconf: warning: mysql:/etc/postfix/mysql_virtual_mailbox_maps.cf: unused
> parameter: password=xxxxxxx
> postconf: warning: mysql:/etc/postfix/mysql_virtual_mailbox_maps.cf: unused
> parameter: dbname=postfix
> postconf: warning: mysql:/etc/postfix/mysql_virtual_mailbox_maps.cf: unused
> parameter: query=SELECT maildir FROM mailbox WHERE username='%u' AND active=1
> postconf: warning: mysql:/etc/postfix/mysql_virtual_mailbox_maps.cf: unused
> parameter: user=postfix
> postconf: warning: mysql:/etc/postfix/mysql_virtual_mailbox_maps.cf: unused
> parameter: hosts=localhost
> 
> In Leap 43.2 this was possible without any issue. Another MySQL/MariaDB
> Client problem in Leap 15? Postfix manpage and sample configurations still
> suggest this as a possibility.

Sorry for being too late. Now I've found that in 3.3.0 a new function 
pcf_check_dbms_client was introduced to "report unknown database client
configuration parameters". This function will be called only if the database
configuration files are given with absolute path. Unfortunately this function
seems to be buggy. But this warnings should not have any influence on the
functionality.