--- a/postfix/pgsql-virtual_mailbox_maps.cf	Mon Dec 05 12:34:29 2011 +0000
+++ b/postfix/pgsql-virtual_mailbox_maps.cf	Mon Dec 05 16:17:01 2011 +0000
@@ -11,4 +11,9 @@
 dbname = mailsys
 
 # The SQL query template used to search the database
-query = SELECT maildir FROM postfix_maildir WHERE address='%s'
+# Use this VIEW-based template if you didn't create the pgsql function
+# `postfix_virtual_mailbox_map'.
+#query = SELECT maildir FROM postfix_maildir WHERE address='%s'
+
+# the recommended, function-based template
+query = SELECT maildir FROM postfix_virtual_mailbox_map('%u', '%d')