we can use postgresql to store postfix configuration.

#apt-get install postfix postfix-pgsql

edit the configuration /etc/postfix/main.cf

alias_maps = pgsql:/etc/postfix/pgsql-aliases.cf

then in /etc/postfix/pgsql-aliases.cf

host =
username=
password=
db_name=
query=
select_field=
table=
where_field=
additional_conditions=

more from postfix documentation