Re: Cache refresh because of hibernate versioning mechanism.

[vkulichenko <va...@gmail.com>]

Hi Czeslaw,

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cszczotka wrote
> I’m using cache with read-through/write-through configuration and with
> database persistent store handled by hibernate Dao –s. Hibernate Dao –s (
> it is legacy code) also handling versioning and optimistic locking. 
> So situation looks like when I put into cache some entity this entity is
> written to database with version 1 set by hibernate but in cache I have
> entity with version 0. Calling get method on cache doesn’t help because
> this entity is in cache and load method from persistance store is not
> called.
> Do you have good way how to force ignite to refresh cache from DB ? I see
> in ignite documentation that I can subscribe on event
> EventType.EVT_CACHE_OBJECT_PUT and programmatically call load method on
> cache. Do you see better way ?  

I think it's better to configure CacheInterceptor and implement reload logic
in onAfterPut method. However, this will be a performance overhead.

-Val



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Re: Cache refresh because of hibernate versioning mechanism.

[vkulichenko <va...@gmail.com>]

One more point. You don't have to and should not pass IgniteCache as a
parameter. Instead, you can inject Ignite into transient field in the
CacheStore implementation and then use it to acquire cache:

@IgniteInstanceResource
private transient Ignite ignite;

-Val



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Re: Cache refresh because of hibernate versioning mechanism.

[vkulichenko <va...@gmail.com>]

Czeslaw,

To achieve best performance you should do data remodeling, get rid of
collections, store different types of objects in different caches and
reference them using foreign keys.

L2 cache can also be an option, but performance wise it will be less
effective.

-Val



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Re: Cache refresh because of hibernate versioning mechanism.

[cszczotka <cs...@interia.pl>]

Hi,
Thanks for your response.
Hibernate dao return object with new version. Version is used for optimistic
locking mechanism. So we have hibernate dao -s and hibernate data model (
*.hbm.xml files). We want to avoid  (if possible) completely rewrite this
code. Another issue will be in our data model where we have a lot of
hibernate entities with one-to-many relation represented by entities
collection ( not id –s collection).  Something similar like User and Posts
relation:
https://github.com/apache/ignite/blob/master/examples/src/main/java-lgpl/org/apache/ignite/examples/datagrid/hibernate/HibernateL2CacheExample.java

The question is also if we are trying to use apache ignite in correct way ?
Maybe only correct way is to use apache ignite as L2 cache  for hibernate
dao –s ? 
Regards,
Czeslaw
 



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Re: Cache refresh because of hibernate versioning mechanism.

[vkulichenko <va...@gmail.com>]

Hi Czeslaw,

Does myEntity object that is returned from DAO have old or new version
value?

Generally, your approach can work, but this looks like a serious performance
overhead. Can you clarify, how exactly this versioning is used? Do you
actually need it after switching to Ignite?

-Val



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Re: Cache refresh because of hibernate versioning mechanism.

[cszczotka <cs...@interia.pl>]

Hi,
I see such solution. Passing to the store reference to cache (loadCache
method has second parameter varargs so I can pass cache here) and in write
method call replace on cache:

public void write(Cache.Entry<? extends MyEntityId, ? extends MyEntity >
entry) throws CacheWriterException {        
MyEntity myEntity = hibernateDao.saveOrUpdate(entry.getValue());
               cache.loadAll(Sets.newHashSet(myEntity.getId()), true, null);
}
Regards,
Czeslaw



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Re: Cache refresh because of hibernate versioning mechanism.

[cszczotka <cs...@interia.pl>]

Hi,
Refer to your advice about implementing CacheInterceptor and onAfterPut
method. It does not help me. It is the same issue - operating on entity copy
because:

in method onAfterPut(Cache.Entry<K, V> entry)  Cache.Entry implementation it
is CacheLazyEntry and if I call entry.getValue I will get entity copy so
setting version on entity copy does not propagated this change to cache.


My question is still open: how to integrate ignite database store handled by
hibernate dao -s with versioning mechanism ?




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