Hi,

codes generated by Ant's hibernate tools usually have a index and a constraint like:

create table info (
id bigint not null auto_increment,
user_id bigint,
primary key (id)
);

alter table info
add index FKAF65AAF96670A934 (user_id),
add constraint FKAF65AAF96670A934
foreign key (user_id)
references user (id);

why there is an index? can it be simply :

alter table info
add constraint FKAF65AAF96670A934
foreign key (user_id)
references user (id);

Indexes allow to find the data in database fast. Adding indexes improves retrieval of data but its optional. so its upon you if u want to use it or not.

PS: For more on index http://en.wikipedia.org/wiki/Index_(database)