ERROR hbm2ddl.SchemaExport  - HHH000389: Unsuccessful: alter table attachment drop constraint FK_8h7b72vyhh4nx4et3t4ms0v22 if exists

public class ImprovedH2Dialect extends H2Dialect {

    @Override
    public String getDropSequenceString(String sequenceName) {
        // Adding the "if exists" clause to avoid warnings
        return "drop sequence if exists " + sequenceName;
    }

    @Override
    public boolean dropConstraints() {
        // We don't need to drop constraints before dropping tables, that just leads to error
        // messages about missing tables when we don't have a schema in the database
        return false;
    }

}