Re: [eclipselink-users] What's the difference between the JoinFetch Anno

[James Sutherland <jamesssss@xxxxxxxxx>]

@JoinFetch means always join fetch the relationship for all queries.
The query hint means just join fetch for this query.
Both should work.  It is very odd that the hint or JPQL is not working.
What version are you using?  Could you include the SQL log on finest.

You should also consider using batch fetching, which is more efficient for a
OneToMany.


Michael Simons wrote:
> 
> Hello,
> 
> I've got a simple one-many Association that I need to query in a single
> select:
> Product (1:N) LocalizedProduct
> class Product {
>  @OneToMany(cascade={CascadeType.PERSIST, CascadeType.REMOVE},
> fetch=FetchType.LAZY,
> mappedBy="product")
> @JoinFetch(value=JoinFetchType.OUTER)
> private Set<LocalizedProduct> locals = new HashSet<LocalizedProduct> (13);
> }
> 
> With the annotation JoinFetch it works like I'd have expected, but it
> doesn't without the
> annotation but giving a QueryHint:
> TypedQuery<Product> query = em.createQuery ("SELECT p from Product p",
> Product.class);
> query.setHint(QueryHints.LEFT_FETCH, "p.locals");
> 
> It also doesn't work with the query:
> TypedQuery<Product> query = em.createQuery ("SELECT p from Product p join
> fetch p.locals",
> Product.class);
> 
> In the last two cases I get (N+1) queries created by EL.
> 
> What do I miss? What do I have to pay attention to?
> 
> Kind Regards, Michael
> 
> 


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