Please create a Jira issue and attach a runnable test case. Thanks, Gail On Thu, Jun 2, 2016 at 5:45 AM, Vladimir Martinek <v...@sykora.cz> wrote:
> Fetch profiles fail to load certain relations because of invalid cycle > detection in MetamodelGraphWalker. Below is an example. > > I have compared the behaviour of Fetch Profiles and standard EAGER > relations (EAGER does not suffer from this problem). The > MetamodelGraphWalker graph walker produces the same results, the SQL is > the same (missing relation). > > With EAGER the relation is loaded in second pass, via > SessionImpl.internalLoad(). There it is decided what LoadType is used - > for eager it uses INTERNAL_LOAD_EAGER, for lazy INTERNAL_LOAD_LAZY. It > does not take into account the fetch profiles here! > > The last place I can get hold of fetch profiles in in > AbstractLoadPlanBasedEntityLoader line 82. After that the fetch profile > information is lost, never making it anywhere near to > SessionImpl.internalLoad(). > > I would like to implement this, but to do that, I need someone to point > me in the right direction. Most of all I need answers to following > questions: > > 1) Is it right to assume the fetch profiles should be evaluated in > SessionImpl.internalLoad() and appropriate LoadType used when detected a > relation affected by a fetch profile? > 2) If so, what is the intended way of getting the fetch profile > information to SessionImpl.internalLoad()? > > Also, a colleague of mine attempted to implement FetchType.SELECT fetch > strategy and ended up with precisely the same problem. I believe solving > my issue would pave way for quick FetchType.SELECT implementation (which > we could also use on our project). > > > Thank you > > Vladimir Martinek > > > Example: > > Have 5 entities - Start, Via1, Via2, Mid and Finish with following > relations (all LAZY): > > Start n:1 Via1 n:1 Mid n:1 Finish > Start n:1 Via2 n:1 Mid n:1 Finish > > Now, trying to use Fetch Profiles to load Start entity and all of its > relations. I would expect Hibernate to execute following SQL select: > > SELECT * FROM Start s > LEFT OUTER JOIN Via1 v1 (path Start-Via1) > LEFT OUTER JOIN Mid > JOIN Finish > > LEFT OUTER JOIN Via2 (path Start-Via2) > LEFT OUTER JOIN Mid > JOIN Finish > > Unfortunately, ii ompletely omits the second join from Mid to Finish, > what I am getting is: > > SELECT * FROM Start s > LEFT OUTER JOIN Via1 v1 (path Start-Via1) > LEFT OUTER JOIN Mid > JOIN Finish > > LEFT OUTER JOIN Via2 (path Start-Via2) > LEFT OUTER JOIN Mid > > I dug deeper into this and found cycle detection in > MetamodelGraphWalker, line 144. Basically, when MetamodelGraphWalker > detects a relation that has already been visited, it considers it a > cycle. But in my case it is not a cycle - I just came to the same > relation twice using two different paths. > > > _______________________________________________ > hibernate-dev mailing list > hibernate-dev@lists.jboss.org > https://lists.jboss.org/mailman/listinfo/hibernate-dev > _______________________________________________ hibernate-dev mailing list hibernate-dev@lists.jboss.org https://lists.jboss.org/mailman/listinfo/hibernate-dev
