This was accidentially posted on NHibernate forum, but it should have been on Hibernate users form:

I have a question concerning how and where to initialize an array in Hibernate 3.

I will have an array of objects instead of java collection
interfaces. Somehow I got a very huge array, with the expected
not-null elements at the end of the array. All other elemtns are NULLs.

Here is the tables:

create table main_table (id number(9) not null, constraint main_pk
primary key (id));
create table sub_table (id number(9) not null, main_id number(9) not
null, constraint sub_pk primary key (id), constraint sub_fk foreign key
(main_id) references main_table (id));

I populated three rows of records on sub_table, with all main_id values
pointing to the primary key of the main_table.

here is the hibernate mapping file:
<array name="subs" cascade="all">
<key column="main_id" />
<list-index column="id" />
<one-to-many class="Sub" />
<array>

but when I called something.getSubs(), I got a very huge (over 2000) array,
only the last three elements were what I populated and expected.

I heard Hibernate array mapping is not as solid as collection interface
mapping. Is that because Hibernate array mapping unables to initialize a correct
length at run-time? Is there any work around on array mapping?

by any chance are the values in your index column starting at 1998? I'm not sure if it is the case with arrays, but with collections hibernate expects indexes to all start at 0. if there are numbers missing or inconsistencies those objects are replaced with nulls in memory.