HHH-7797 forced uniqueness to be defined by constraints through alter table statements. HHH-8092 identified that this was not occurring on schema updates.

Since HHH-1904 resulted in non-explicitly-named constraint names using randomly-generated characters, checking for a constraint's existence prior to creating it on a schema update is not always possible. This leads to errors.

We cannot simply remove unique constraint generation on an update all-together. Instead, let's make it configurable. A property would select from the following:

1.) Update ignores all unique constraints
2.) Update attempts to (re-)create the unique constraints and ignores any errors

I'd argue that #2 would be the default.