[FAQ] Re: ObjectCacheEmptyImpl regurgitating

[Thomas Mahler <th...@web.de>]

Hi Jason,

The Problem you see is due to circular references in your data.
Say A references B and B has a backreference to A.

Now we load A from the DB. If autoretrieve="true" for the 
reference-descriptor describing the reference to B, OJB will also load B.
If autoretrieve="true" for the B-reference-descriptor describing the 
back-reference to A, OJB must retrieve A.
And here is the key point.

If we use the defaultcache A will be in the cache already, as it was 
loaded first. So OJB will simply lookup A from the cache. No endless 
recursion!

But if we use the emptycache, A will not be cached. So OJB must load A 
from the DB. And then again B is retrieved, etc., etc.
There's you endless recursion.

In other words: A non-empty cache is needed to allow proper loading of 
circular references. (Other O/R tools like TopLink work the same way).

If you still want to use the EmptyCacheImpl you should set 
autoretrieve="false" and load references explicitely by 
broker.retrieveReference(...).

cheers,
Thomas



Jason McKerr wrote:
> I just tried to turn caching off by using ObjectCacheEmptyImpl setting
> in ObjectCacheClass, and it seems to continuously loop through the SQL
> statement infinitely.  The default works fine though.
> 
> Any ideas why this might be?
> 
> Jason
> 
> 
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