Using SHA256/512 for SQL based password

[Robert Moskowitz via dovecot]

I have trying to find how to set the dovecot-sql.conf for using 
SHA256/512.  I am going to start clean with the stronger format, not 
migrate from the old MD5.  It seems all I need is:

driver = mysql connect = host=/var/lib/mysql/mysql.sock dbname=postfix 
user=postfix password=$Postfix_Database_Password default_pass_scheme = 
SHAxxx-CRYPT # following should all be on one line. password_query = 
SELECT username as user, password, concat('/home/vmail/', maildir) as 
userdb_home, concat('maildir:/home/vmail/', maildir) as userdb_mail, 101 
as userdb_uid, 12 as userdb_gid FROM mailbox WHERE username = '%u' AND 
active = '1' # following should all be on one line user_query = SELECT 
concat('/home/vmail/', maildir) as home, concat('maildir:/home/vmail/', 
maildir) as mail, 101 AS uid, 12 AS gid, 
CONCAT('*:messages=30000:bytes=', quota) as quota_rule FROM mailbox 
WHERE username = '%u' AND active = '1'

where xxx is either 256 or 512. All the rest I have been finding in my 
searches concern converting the format and are not needed for a clean start?

thanks