Re: [eclipselink-users] Fetchgroup usage / unfetched basic attributes

["Hahn, Markus" <Markus.Hahn@xxxxxxxxxxxxx>]

Hi Andrei,
we found out that using LoadGroup instead of FetchGroup fits better to our needs, it looks like all basics are loaded even if they are not noted in the LoadGroup. Does this happen by accident? Or can You confirm this behaviour as intended? We didn't find anything in the docs.
Best regards, Markus

-----Ursprüngliche Nachricht-----
Von: eclipselink-users-bounces@xxxxxxxxxxx [mailto:eclipselink-users-bounces@xxxxxxxxxxx] Im Auftrag von Andrei Ilitchev
Gesendet: Freitag, 2. September 2011 15:22
An: eclipselink-users@xxxxxxxxxxx
Betreff: Re: [eclipselink-users] Fetchgroup usage / unfetched basic attributes

Hi Markus,

If there is no LAZY basics and a query is executed without a FetchGroup 
then all basics are fetched.

In other words lack of a FetchGroup is equivalent to a FetchGroup that 
includes all the attributes.

Default FetchGroup is created automatically if there is at least one 
basic attribute annotated with fetch=LAZY.
It would make sense to use fetch=LAZY for a basic attribute if it's 
mapped to potentially huge object that is rarely used (for instance 
array of bytes mapped to a Blob).

If something like that is not the case then I would not use fetch=LAZY 
for basics.

Thanks,
Andrei

On 9/2/2011 6:03 AM, Hahn, Markus wrote:
> Hi Andrei,
> 1. simple example: I suppose, the cases where we get the basics loaded, are those without Fetchgroups so it fits to what you said.
> 2. what we are trying to do? Well, we migrated from JDO to JPA, and that's the default in JDO. In general, I am convinced that it would be a valuable feature to include the basic mappings in a default Fetchgroup which can be a starting point to enlarge. What is an entity without basics like Strings, Long, Integer?
> Thanks a lot and best regards, Markus
>
>
> -----Ursprüngliche Nachricht-----
> Von: eclipselink-users-bounces@xxxxxxxxxxx [mailto:eclipselink-users-bounces@xxxxxxxxxxx] Im Auftrag von Andrei Ilitchev
> Gesendet: Donnerstag, 1. September 2011 16:39
> An: eclipselink-users@xxxxxxxxxxx
> Betreff: Re: [eclipselink-users] Fetchgroup usage / unfetched basic attributes
>
> Comments are inline.
> On 9/1/2011 10:20 AM, Hahn, Markus wrote:
>> Hi Andrei,
>> thanks a lot. But then i dont understand why we have so many use cases where we define a Fetchgroup without basic attributes on a query, and despite of not included in the Fetchgroup they are loaded in the entities. What could cause this behaviour?
> Could you please provide a simple example.
>> And is there a convenient way to build a Fetchgroup including all the basic attributes?
> I don't think there is anything like that.
> What are you trying to do?
> To always fetch all basic attributes just don't define them as LAZY -
> and you would not need any fetch group on queries.
> And use a FetchGroup when you need to NOT fetch some basic attributes.
>> Best regards, Markus
>>
>> -----Ursprüngliche Nachricht-----
>> Von: eclipselink-users-bounces@xxxxxxxxxxx [mailto:eclipselink-users-bounces@xxxxxxxxxxx] Im Auftrag von Andrei Ilitchev
>> Gesendet: Donnerstag, 1. September 2011 15:16
>> An: eclipselink-users@xxxxxxxxxxx
>> Betreff: Re: [eclipselink-users] Fetchgroup usage / unfetched basic attributes
>>
>> Hi Markus,
>>
>> If you don't use a fetch group with a query the only basic attributes
>> that are NOT fetched are those defined as "fetch=LAZY".
>>
>> Alternatively, if you use a fetch group with a query the only basic
>> attributes fetched are those included in the fetch group.
>>
>> Thanks,
>> Andrei
>>
>> On 9/1/2011 6:14 AM, Hahn, Markus wrote:
>>> Hi folks,
>>> we use the EL Fetchgroup features and encounter some behaviour we cant
>>> explain.
>>> In many cases, EL works as expected concerning the basic mappings
>>> (String, Long..): the attributes are fetched if they are not mapped as
>>> "fetch=LAZY", independently of using a Fetchgroup on the query. Basic
>>> mappings don't have to be included in the Fetchgroup.
>>> In some cases, this does not work: the basic attributes are NOT loaded.
>>> If we add them to our Fetchgroup, they are loaded.
>>> Is it a bug? Does anybody has a hint how to solve this problem?
>>> Best Regards, Markus
>>>
>>>
>>>
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