Doctrine has a few specific attributes available that allow you to specify the default values of things that in the past were hardcoded values. Such as default column length, default column type, etc.
It is possible to specify an array of default options to be used on every column in your model.
// bootstrap.php
// ...
$manager->setAttribute(Doctrine::ATTR_DEFAULT_COLUMN_OPTIONS,
array('type' => 'string', 'length' => 255, 'notnull' => true));
You can customize the properties of the automatically added primary key in Doctrine models.
$manager->setAttribute(Doctrine::ATTR_DEFAULT_IDENTIFIER_OPTIONS,
array('name' => '%s_id', 'type' => 'string', 'length' => 16));
The %s string in the name is replaced with the table name.