Post subject: Setting LAZY or EAGER per-call, not per-class

Posted: Sat Mar 14, 2009 2:08 am 

Hi,

LAZY or EAGER fetch strategy can be set for class member collection mapping.

However, in most cases, I would prefer to set fetching strategy for each distinct call of session manager API. I can't have everything as EAGER, because it would load whole DB. And having something LAZY forces me inevitably to 1+N SELECTs problem.

Please, is there any way to specify fetching type when calling e.g. find(...)?

Thanks,
Ondra

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Posted: Sat Mar 14, 2009 7:44 am 

Hi Ondra,

in HQL queries, you can use the "left join fetch" construct to specify that you want to eagerly fetch some association, independently of what is specified in the mapping file. E.g. you could issue the following query to eagerly fetch the "children" collection of a Person:

Is this what you're looking for?

However, I don't know any way to change the fetching strategies when you are not using HQL but methods like Session#get and Session#load in which case only the settings in the mapping file are honoured.

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Posted: Sat Mar 14, 2009 1:30 pm 

Thanks ojm,

The HQL tip is fine, but isn't exactly what I need.

I need to set fetching type for entities loaded using get() etc, as you wrote in the last paragraph.

Any further tips?

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Posted: Mon Mar 16, 2009 7:27 am 

Hi,

I'm looking for exactly the same thing but Hibernate allows the fetching strategy to be changed only through HQL or the Criteria API. I wish the load() or get() api could also accept a parameter specifying EAGER or LAZY loading. I really dont want to write separate HQLs to load eagerly and use the usual load api in other cases. It should be possible to do so using the same api.

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Posted: Mon Mar 16, 2009 7:35 am 

Its not possible to change the fetch-style for find().
However you could also use Criteria to change the fetch-style.

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Posted: Mon Mar 16, 2009 7:39 am 

Hi,

Thanks. But dont you feel it would be better to be able to do so through API? Instead of me having to write an HQL to fetch all my associations using joins, hibernate can do so internally if i pass the appropriate flag in load(). Currently, I need to have two mechanisms - use HQL or Criteria to fetch everything and load to lazy load.

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Posted: Mon Mar 16, 2009 7:48 am 

Yes, I also think it would be nice to manipulate the fetch-strategy at runtime.

Maybe there will be something like that in the next version.