When you make an existing column in a table mandatory (and no default value is set), you get a very helpful validation warning you to setup the data migration for this column.
When you create a unique index on an existing column (or set of columns), no validation will be shown.
It would be nice to have a warning in the validations list to show the developer that this could lead to issues.
New
New unique constraint validation
+8- Captain
Enter your E-mail address. We'll send you an e-mail with instructions to reset your password.