Hi, the uniqueConstraint and many others are used only if you want automatic schema generation, which means that you let hibernate to generate your database, and these constraints will be applied then, the same is the length of a
String property, it will be used only so that when creating the schema it will replace the (x) variable with it varchar(x).
and this is the whole purpose of this meta data, however if you don't automatically generate your schema, and instead you are writing it by hand then hibernate will just ignore these values, as if they did not exist.