Re: lazy:true, belongsTo defined => eager fetching of whole database on update
All related records are loaded during validation process. To prevent this behavior you can use modelObject.save(deepValidate:false), but you must do manual validation on all associasions in that case, including embedded :(
I don't know is there a way to validate only loaded or changed associaded objects
Is it intended that if belongsTo is defined on a relation, that this results into eager fetching of records on update of a parent record?