join « Fetch « JPA Q&A





1. JPA: please help understanding "join fetch"    stackoverflow.com

I have the following entity structure: Business --> Campaign --> Promotion, where ONE Business can have MANY Campaigns and ONE Campaign can have MANY Promotions. Both one-to-many relations are declared as ...

2. Hibernate noob fetch join problem    stackoverflow.com

Hi all I have two classes, Test2 and Test3. Test2 has an attribute test3 that is an instance of Test3. In other words, I have a unidirectional OneToOne association, with test2 having ...

4. JPA native join fetch    stackoverflow.com

It's well known that we can retrieve an entity and all its children in a single JPQL query using join fetch. However, I can't seem to get this working with a ...

5. Hibernate fetch="join"    coderanch.com

Hi Due to performance reasons when mapping a 1-M relationship I needed the set of objects to be populated from one sql statement straight away. I set lazy="false" and the set was populated immediately *BUT* using multiple SQL statements. After reading through the reference guide and a general google I was pretty sure fetch="join" was all I needed. However, when I ...

6. Hibernate ignore fetch="join"    forum.hibernate.org

I have an object content that have a collection of roles. I want to make a select, using criteria, of contents that have no roles. Code: Criteria createCriteria = session.createCriteria(Content.class); createCriteria.add(Restrictions.isEmpty("allowedRoles")); createCriteria.setFetchSize(200); ... ...

7. @Fetch(JOIN) not working    forum.hibernate.org

Hello there! Given this association: @ManyToOne(fetch=FetchType.EAGER) @Fetch(FetchMode.JOIN) @JoinTable(name="MEDIA_CATEGORY",joinColumns={@JoinColumn(name="MEDIA_ID")},inverseJoinColumns={@JoinColumn(name="CATEGORY_ID")}) private Category category; I was expecting Hibernate to load the Category in a single select. Instead: /* load org.acme.model.media.AbstractMedia */ followed by : /* load org.model.category.Category */ I wonder if this is caused by the JoinTable... BTW. Is the default behavior of Hibernate to create left joins for all associations, no matter if ...

8. Doubt about Fetch Join    forum.hibernate.org

String jpql = "select u from User u "; jpql += "join fetch u.groups g "; jpql += "where u.name = 'John' "; jpql += "and g.id = 123 "; Query query = em.createQuery(jpql); User result = (User) query.getSingleResult();

9. Custom constructor and JOIN FETCH problem    forum.hibernate.org





10. Very newbie question on join fetch, please help?    forum.hibernate.org

11. Hibernate JPA 1.0 multiple join fetch not supported?    forum.hibernate.org

All, Setup: JPA 1.0 jars, TransactionType=JTA, TransactionAttribute=NOT-SUPPORTED for EJB3 SLSB Issue: using EJBQL, if just one "left outer join fetch", the object and association are both initialized. If an additional join fetch is added, no association is initialized and I got LazyInitialization error when accessing. e.g. select a from A a left outer join fetch a.B b => both a and ...

13. deep join fetch with one-to-many in path    forum.hibernate.org

14. Join versus fetch join    forum.hibernate.org

Hello everyone, We're trying to determine by HQL when a lazy collection will be join-loaded. We're using fetch join but we get what it seems a strange result. This HQL query works well: select distinct d from DescripcioAssignatura d join d.fontsInformacio (in fact, kinda "select distinct p from parent p join p.children") It results in 4 rows, but it doesn't load ...

15. fetch join    forum.hibernate.org

16. why shouldn't we use 'where' with 'fetch join' ?    forum.hibernate.org

I reply to myself, as I've done some more tests, and found that my latest reply is pure nonsens Even with a bidirectional association I'm not able to navigate from T1 to T3, coz the framework triggers the lazy fetching for the non initialized T2 and T3 So, the conclusion is : I must use an inverse=true relationship, and I must ...





17. Fetch Joining problem    forum.hibernate.org

I'm having a pretty serious fetch joining problem. I've went back to an older application that I wrote a long time ago. It's not a mess, but my Hibernate skills were not nearly as competent as they are now. Anyhow, fetch joining with collections doesn't seem to work correctly on this project as it does on others, and I'm having trouble ...

18. using fetch join or not    forum.hibernate.org

Hibernate version:2.16 The generated SQL (using fetch join): Code: Hibernate: select this.studentcode as studentc1_11_, this.name as name11_, this.identitynumber as identity3_11_, this.birthday as birthday11_, this.entrancedate as entrance5_11_, this.recruitarea as recruita6_11_, this.isvalidator as isvalida7_11_, this.classcode as classcode11_, this.entrancetypecode as entrance9_11_, this.nationcode as nationcode11_, this.partycode as partycode11_, this.sexcode as sexcode11_, this.studenttypecode as student13_11_, this.nativeplace as nativep14_11_, this.schoolareacode as schoola15_11_, this.origincode as origincode11_, classlibra1_.code as ...

19. stackoverflow with fetch="join"    forum.hibernate.org

20. many-to-one + fetch join    forum.hibernate.org

CLASS A Report KF_SEQ_REPORT

21. join fetch and group by    forum.hibernate.org

22. join fetch    forum.hibernate.org

...

23. Indexing affects fetch="join"?    forum.hibernate.org

Hi, It looks like using the "join" fetch strategy might be dependent on indexing the proper columns? The bidirectional many-to-one mapping I have below will work, but if I remove the indexing on Activity's FLOW_ID column, I get an "illegal access to loading collection error" (the error would come up on the query in my code below). I think this is ...

24. JOIN FETCH and setMaxResult    forum.hibernate.org

25. Many-to-one fetch="join" quiz    forum.hibernate.org

26. Redundant sqls after join fetch    forum.hibernate.org

Newbie Joined: Mon Oct 10, 2005 1:07 pm Posts: 13 Hi, I have a class (CategoryMap below) with many-to-one mapping to another class (CategoryMapType). I execute the following HQL: Code: from CategoryMap as map join map.type join fetch map.sourceCategory as source join fetch map.targetCategory as target where map.type=? and I get the follwing SQLs executed: Code: Hibernate: /* from CategoryMap ...

27. fetch="join" not working    forum.hibernate.org

Hello, I have an object Route which has a one-to-many association to Path. From Route.hbm.xml: When I load or fresh Route, all Paths get pulled in as a single select with a join clause (as expected). My problem arises when I try to add a collection ...

28. fetch="join"    forum.hibernate.org

29. one-to-one/many-to-one fetch="join" not working.    forum.hibernate.org

Hibernate version: 3.1.3 Name and version of the database you are using: Postgres 8.1 Hello, I'm having a strange problem with one-to-one relationship. I having the following mappings: People.hbm.xml: Code:

30. Join fetch not working the way I want it to    forum.hibernate.org

Hi, I have a simple one to many relation between MachineClass and MachineDataInstance tables. There are 6 entries in the MachineClass. I want to write a query that will get me a list of 6 MachineClass objects and initialize the Set member variable of all the related MachineDataInstance instances. So I use the following query: [code] List list = session.createQuery("select distinct(mc) ...

32. Fetch.JOIN    forum.hibernate.org

I have a question about the use of Fetch.JOIN I would like some advice on. The gui I am developing is seperate from the business tier and therefore I am 'preparing' the objects I need so that I dont get Lazy exceptions. 99% of the non-lazy configuration is done using Fetch.JOIN as apposed to in the xml mappings because other systems ...

33. Fetch join vs Hibernate.initialize()    forum.hibernate.org

I have an Item class that has a collection bids. By default (Hibernate 3) my pojo is lazy so when I want to getBids() I need first to Hibernate.initialize(item) so as later to have item.getBids(); Correct? I read in a book that I use another lazy strategy and do something like that: Criteria criteria = session.createCriteria(Item.class); criteria.setFetchMode("bids", FetchMode.JOIN); List allItems = ...

34. Using fetch="join" and expected behaviour?    forum.hibernate.org

Newbie Joined: Mon Mar 12, 2007 2:47 pm Posts: 11 I've recently had issues with performance with getting a list of Objects which has as one of it's properties a Set of other objects. Essentially, our Banner class has a Set of bannerClickHistory objects which is a one-to-many mapping. When i go and grab a list of banners, i would also ...

35. many-to-many - how to "fetch join" correctly?    forum.hibernate.org

I have bi-directional many-to-many relationship between two entities, let's say Department and Employee. In the database this is realized through the two main tables DEPARTMENT and EMPLOYEE and the intermediary table DEP_EMP. In the Java classes this relationship is defined through collections (Set) and is mapped as follows: -- from Department.hbm.xml --

36. Fetching with join problem    forum.hibernate.org

I don't get it. I have the following setup: 2 clases: public class ClientOrder { private int orderId; private String orderNo, orderState; private Client orderClient; private Date orderDate, stateDate; private Address address; private double totalNet, totalVat, totalGross, amountPayed; private Set orderLines;} public class Client { private int clientId; private Address address; private String firstName; private String lastName; private String login; private ...

37. fetch="join" ignored    forum.hibernate.org

... S_BM_ITEM ...

38. when should i use one-to-many fetch="join"    forum.hibernate.org

1. Yes, fetch="join" disables lazy loading. i.e. enables eager loading. The said book says so right after the excerpt you have quoted. But there is a way to eagerly fetch without using fetch="join". You could eagerly fetch using separate selects instead of joins in the same (one) select by using fetch="select" together with lazy="false". The best way to think about it ...

39. Problem with fetch join    forum.hibernate.org

40. Join fetch problem    forum.hibernate.org

I have a strange problem with join fetching. I have a parent class Constraint with a child class ConstraintTrigger. It is mapped as follows: Code: Constraint ...

41. LazyInitilizationException with JOIN FETCH    forum.hibernate.org

Shouldn't child to grandchildren be one-to-many and grandchildren to child many-to-one? Otherwise it would mean that the several children could have the same grandchild. The point with your first query is, you only retrieve one(1) grandchild which can have an (yet unknown) number of associated children. So your solution is actually right for your problem though i still would suggest reconsiderung ...