Question

Ok, I have an entity class with a List member that maps through Hibernate to a large list of objects. I do not need to fetch the entire list at query time, I only need the total size of objects that this applies to.

• List also uses the @Where annotation to only select a
  subset of the elements.
• List is marked as
  @LazyCollection(LazyCollectionOption.EXTRA) due to its very large size
• Mapping is done through the use of a link table
• List has the following sort of mapping:

The @JoinTable of the List uses a join on table 2 and an inverse join on table 3. I am not entirely sure what the SQL generated is because I am not too fluent in SQL.

Anyways, the @Where clause will have some restrictions on it, such as ‘STATUS = ACTIVE’ and possibly some other stuff such as ‘LETTER = ‘A’. Like the example shows, if I do a call like this:

List items = Lists.getItems();
items.size();    // This results in 1 with the restrictions with the @Where clause

The above populates the items with the correct items from Table 3 with the restrictions of the @Where clause.
The first thing I tried without fetching the entire list was this:

int listSize = Lists.getItems().size();     // This results in 3, the @Where clause is not applied

I researched it, and found this issue with Hibernate that I do not believe has been fixed: Hibernate Jira

So, my question is what is the best way to do this? I am not very proficient in SQL or HQL, yet. I am not too familiar with joins and other database terminology, so if any support could be given that would be great.

Thanks!

Answer 1

I ended up doing the following query and setting the parameter:

public int getActiveCountOfList(long list_id) {
    String sql = "SELECT COUNT(*) FROM TABLE_2 t2 
                 LEFT JOIN TABLE_3 t3 ON t2.ITEM_ID = t3.ITEM_ID 
                 WHERE t2.LIST_ID = :list_id AND t3.LETTER IN ('A', 'B')
                 AND t3.STATUS = 'ACTIVE'";

    Object result = session.createSqlQuery(sql).setLong("list_id", list_id)
                       .uniqueResult();

    return ((Number) result).intValue();
}