I am using the PostgresSQL module for SilverStripe.

My issue is that I can define relations with for example:

public static $has_one = array(
'PageRedirect' => 'SiteTree',
);

What this will code do is that it will create the database with a Indice with the naming pattern: ix_tablename_pageredirectId
However no foreign key is created.

Further SilverStripe seems to write "0" instead of "null" in columns that are empty relations. So actually you can't even create those foreigh key contraints as SIlverStripe will constantly violate them.

How can one configure SilverStripe for proper Foreign Key Contraints in the database?

Thanks!
Sebastian