The field length of the document name field is 248 characters out of the box. How do I increase the length of this field. I assume it's mapped to the the dtree.name column.
You are correct that there is a link between the two fields, but it is not enforced or set, so if you change one you would need to manually change the other as well.
Any changes like this to the base schema are likely to cause issues later on - I've seen Service Pack and Upgrades fail if the database is non standard like this.
Why do you need it longer ?