org.hibernate.shards
Class CrossShardAssociationException

java.lang.Object
  java.lang.Throwable
      java.lang.Exception
          java.lang.RuntimeException
              org.hibernate.exception.NestableRuntimeException
                  org.hibernate.HibernateException
                      org.hibernate.shards.CrossShardAssociationException

All Implemented Interfaces:

Serializable, org.hibernate.exception.Nestable

public class CrossShardAssociationException
extends org.hibernate.HibernateException

Exception thrown when someone attempts to create a cross-shard association. Here's an example of a cross-shard association. Let's say we have AccountManager and Account. There is an owned, one-to-many relationship between AccountManagers and Accounts, and we are sharding by AccountManager. That means an AccountManager and all her Accounts live on the same shard. Now suppose you did the following: public void reassignLeastProfitableAccount(AccountManager mgr1, AccountManager mgr2) { Account acct = mgr1.removeLeastProfitableAccount(); acct.setAccountManager(mgr2); mgr2.addAccount(acct); } If the 2 managers happen to live on different shards and you were to then attempt to save the second manager you would receive a CrossShardAssociationException because the account lives on a different shard than the manager with which you're attempting to associate it. Now you'll notice a few things about this example. First, it doesn't really respect the constraints of an owned one-to-many relationship. If AccountManagers truly own Accounts (as opposed to just being associated with them), it doesn't makes sense to reassign an account because the AccountManager is part of that object's identity. And If the relationship is an association then you probably shouldn't be using Hibernate Sharding to manage this relationship because Accounts are going to pass between AccountManagers, which means Accounts are going to need to pass between shards, which means you're better off just letting Hibernate manage the relationship between AccountManagers and account ids and loading the objects uniquely identified by those ids on your own. The other thing you'll notice is that if the two managers happen to live on the same shard this will work just fine. Yup, it will. We can detect cross-shard relationships. We can't detect risky code. You just need to be careful here.

Author:

maxr@google.com (Max Ross)

See Also:

Serialized Form

Field Summary

Fields inherited from class org.hibernate.exception.NestableRuntimeException

delegate

Constructor Summary

CrossShardAssociationException(String s)

CrossShardAssociationException(String string, Throwable root)

CrossShardAssociationException(Throwable root)

Method Summary

Methods inherited from class org.hibernate.exception.NestableRuntimeException

getCause, getMessage, getMessage, getMessages, getThrowable, getThrowableCount, getThrowables, indexOfThrowable, indexOfThrowable, printPartialStackTrace, printStackTrace, printStackTrace, printStackTrace

Methods inherited from class java.lang.Throwable

fillInStackTrace, getLocalizedMessage, getStackTrace, initCause, setStackTrace, toString

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

CrossShardAssociationException

public CrossShardAssociationException(Throwable root)

CrossShardAssociationException

public CrossShardAssociationException(String string,
                                      Throwable root)

CrossShardAssociationException

public CrossShardAssociationException(String s)