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From "Alexander Saint Croix" <saintx.opensou...@gmail.com>
Subject Re: EntityManger close against the Query and lazy Loading
Date Wed, 16 Jan 2008 17:25:06 GMT
Yep, defining fetch groups could help you here.  I have this same behavior
in a number of entities with multiple collection-valued references.  Here
are some links to the doco on this subject which you might find useful:

http://openjpa.apache.org/docs/latest/manual/manual.html#ref_guide_fetch
http://openjpa.apache.org/docs/latest/manual/manual.html#openjpa.FetchGroups
http://openjpa.apache.org/docs/latest/manual/manual.html#jpa_overview_join_fetch
http://openjpa.apache.org/docs/latest/manual/manual.html#jpa_hints_fetchplan
http://openjpa.apache.org/docs/latest/manual/manual.html#jpa_langref_fetch_joins
http://openjpa.apache.org/docs/latest/manual/manual.html#jpa_langref_fetch_joins

Cheers,
--
Alex




On Jan 16, 2008 10:53 AM, SomuReddy <chowdareddy.somu@gmail.com> wrote:

>
> Hi Alexander,
>
> Thanks for your information, but I am not using the any join( LEFT JOIN
> FETCH)  in query, I am just specifying the relationship like this..
>
> @OneToMany(mappedBy = "fireRsrcDO", cascade = CascadeType.PERSIST)
>    List<FireRsrcVersionDO> fireRsrcVerDOList = null;
>
> by defaullt OneToMany fatch type is "lazy loading", so problem is when i
> close the EntityManager after execution of query(Query is  executing on
> one
> of the dataobject where i specified all these relationships) , data is not
> fetching.
> Can i use the fetch groups here???
>
> Thanks,
> Somu
>
>
> Alexander Saint Croix-2 wrote:
> >
> > Hi.
> >
> > You should look into using the LEFT JOIN FETCH clause in your query, and
> > perhaps should also look at whether some of your collection valued
> > references can be set to FetchType.EAGER without causing the cascading
> to
> > spiral out of control and pull down the entire database.  A third
> solution
> > is to look into using Fetch Groups.
> >
> > HTH,
> > --
> > Alexander R. Saint Croix
> > (a user, like you)
> >
> >
> >
> >
> > On Jan 15, 2008 3:05 PM, SomuReddy <chowdareddy.somu@gmail.com> wrote:
> >
> >>
> >> Hello,
> >>
> >> I am creating the own EntityManger for each query to execute?  is it
> >> required to close the EntityManger after execution of the each Query, I
> >> have
> >> lazy loading(fetch type) on my data objects with some
> relationships(like
> >> OnetoMany, ManytoOne and ManytoMany), If I close the EntityManger after
> >> the
> >> Query execution, i couldn't  get data thru relationships as it defined
> >> fetch
> >> type is "Lazy" and EntityManger is no more active.
> >>
> >> is there any other soultion except changing the fetch type is from lazy
> >> to
> >> Eager.. or I  should not close the EntityManger after query execution,
> If
> >> I
> >> won't close the EntityManager what are the Cons?????
> >> when EntityManager instance will be garabage collect????
> >>
> >> Any idea on this???
> >>
> >>
> >> --
> >> View this message in context:
> >>
> http://www.nabble.com/EntityManger-close-against-the-Query-and-lazy-Loading-tp14847417p14847417.html
> >> Sent from the OpenJPA Users mailing list archive at Nabble.com.
> >>
> >>
> >
> >
>
> --
> View this message in context:
> http://www.nabble.com/EntityManger-close-against-the-Query-and-lazy-Loading-tp14847417p14885514.html
> Sent from the OpenJPA Users mailing list archive at Nabble.com.
>
>

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