PLease let us lock tables and relationships to protect them from sync.
I run a non trivial database - some hundreds of tables. We often use (sql server) views to generate statistical data for entities (i.e. they see how many sub objects are there etc.) so that we can easilfy filter by them (some of those views include some quite complex properties.
Views can not have primary keys. Mine have them (i.e. they are not double) but I can not set that up in SQL Server.
In order to us them properly I have to manually define a primary key and then I can use an association between the view and the entity.
That is, until the next sync (we do database first) when the sync window then tries to delete every single primary key. Every. Time.
Given that I have a large number of such artificial keys and a lot to sync it turns a simple sync into a one hour nightmare multiple times a day with the slightest mistake (overlooking something) resulting in another hour.
if I can mark elements as "keep" then those could be ignored in the sync as long as possible (I.e. only show the primary key when a field has changed) and it would turn this hour long issues back into a one minute sync.