Re: [eclipselink-users] Fetching with eclipselink

[Leon Derks <leon.derks@xxxxxxxxxx>]

Hi Gordon,

Thanks for the tip. But does this result in two different queries?
One for loading the Product (maybe from cache) and one for loading the 
Category(maybe from cache)?

And how can I let Eclipselink do the work, without using my named query?

I have a loadProductById, that loads the product, but not its Category. 
How can Eclipselink load the category from cache?
And how do I know if an object is in the cache?

Leon





Gordon Yorke wrote:
> Hello Leon,
>    See email from Tom Ware, but I would like to add that if you have 
> not disabled caching and in your application you would expect the 
> Category object to be in the cache, you will get much better 
> performance not joining this relationship but allowing EclipseLink to 
> retrieve the related object from the cache without a database query at 
> all.  For those times when you know that Category will not be in the 
> cache you can use the named query.
> --Gordon
>
> Leon Derks wrote:
> > Hello
> >
> > I have an object Product with a @ManyToOne relation to a Category 
> > Object.
> >
> > Default the fetch type of this relation is EAGER (Category is loaded, 
> > when Product is loaded).
> > But when I load a Product by Id, I see there is a second select that 
> > loads the Category object.
> >
> > This is not what I want. Why doesn't eclipselink translates 
> > thisautomatically in one single query?
> >
> > I temporary solved this by defining a named query: select p from 
> > Product p inner join fetch p.category where p.id = :productId.
> >
> > Now a product and its category are loaded in one select statement.
> >
> > Is there a way to let eclipselink automatically load the objects in 
> > one select or do I always have to use a named query for this?
> >
> > Leon
> > _______________________________________________
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> > eclipselink-users@xxxxxxxxxxx
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