RE: [eclipselink-users] Object in EntityManager conext: no cache setting

[Andrei Shakirin <andrei.shakirin@xxxxxxxxx>]

Hi Tom,

Thanks a lot for useful and comprehensive response.

Query hints can be elegant solution for my case.

Regards,
Andrei. 

-----Original Message-----
From: eclipselink-users-bounces@xxxxxxxxxxx [mailto:eclipselink-users-bounces@xxxxxxxxxxx] On Behalf Of Tom Ware
Sent: Dienstag, 30. März 2010 15:12
To: EclipseLink User Discussions
Subject: Re: [eclipselink-users] Object in EntityManager conext: no cache settings are relevant?

Hi Andrei,

   In the situation below, the cache settings will not be relevant.  When you have an entity that is in the managed state, (it is in the EM context), you will have to somehow do a refresh to get new data from that database - this is just the way JPA works.

   Aside from refresh and clear, you can use our query hints to cause a refresh:

http://wiki.eclipse.org/Using_EclipseLink_JPA_Extensions_%28ELUG%29#Refresh

   This can be used in any query and additionally, in JPA 2.0 provided in the list of properties that in em.find(Class<T> entityClass, Object primaryKey,
                       Map<String, Object> properties)

   The scenario where you might want to play with the cache settings, is if in
#3 you were using a different entityManager.  In that case, you should use the cache settings to disable shared caching.  See the "shared" setting on the Cache annotation here:

http://wiki.eclipse.org/Using_EclipseLink_JPA_Extensions_%28ELUG%29#Using_EclipseLink_JPA_Extensions_for_Entity_Caching

-Tom


Andrei Shakirin wrote:
> Hello everyone,
>  
> I need a short advice regarding EclipseLink cache settings.
>  
> Imagine the following situation:
> 1. JPA Client reads the entity using EntityManager. So entity becomes 
> into EM context.
> 2. Other external SQL client deletes this entity from the DB.
> 3. JPA Client reads the entity again using the same EM.
>  
> Question: are EM.refresh(entity) or EM.clear() only the ways to force 
> EM to re-read entity on step 3?
> Is it possible to achieve it also using any EclipseLink cache settings?
>  
> The following properties don't affect EM behavior in this case:
>                 <property name="_eclipselink_.cache.shared.default" 
> value="false"/>
>                 <property name="_eclipselink_.cache.type.default" 
> value="NONE"/>
>  
> Regards,
> Andrei.
>  
>  
>  
> 
> 
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