[Acegisecurity-developer] Acegi Database tables issue

[Marco Mistroni]

hello all,
   i m using acegi in my webapplication...
i copied the code for populating acegi tables from the sample application..
everything has worked fine so far, but recently i decided to include dbunit in my
webapp in order to import existing database... and i got exceptions mainly
because the authorities table does not have a primary key

i went to have a look at theh source code..  SQL code was this

 template.execute (
             "CREATE TABLE AUTHORITIES(USERNAME VARCHAR_IGNORECASE(50) NOT NULL,AUTHORITY VARCHAR_IGNORECASE(50) NOT NULL,CONSTRAINT FK_AUTHORITIES_USERS FOREIGN KEY(USERNAME) REFERENCES USERS(USERNAME));");
        template.execute(
             "CREATE UNIQUE INDEX IX_AUTH_USERNAME ON AUTHORITIES(USERNAME,AUTHORITY);");


not being a db whiz,  i m not clear on what is the difference between creating this index as opposed tocreate a primary key...

anyone could help?

thanks in advance and regards
  marco