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
