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kiran7881
 Post subject: How setCacheable of Query will work
PostPosted: Tue May 12, 2009 1:37 am 
Beginner
Beginner

Joined: Wed May 06, 2009 12:23 pm
Posts: 23
I have created a query for select Operation in Hibernate using
Code:

Query query =session.createQuery("select from Book book where book.bookname =?");                           
query.setParameter(0,"Hibernate",Hibernate.STRING);
query.setCacheable(true);


Please tell me where exactly the cache with Query will get stored upon ??(I am ot using second level Cache)

Thanks in advance
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nordborg
 Post subject: Re: How setCacheable of Query will work
PostPosted: Tue May 12, 2009 3:12 am 
Expert
Expert

Joined: Wed Mar 03, 2004 6:35 am
Posts: 1240
Location: Lund, Sweden
Query results are cached in the second-level cache, so you need to enable this. Check this documentation:

http://docs.jboss.org/hibernate/stable/ ... cache.html
http://docs.jboss.org/hibernate/stable/ ... cache.html
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cgs
 Post subject: Re: How setCacheable of Query will work
PostPosted: Tue May 12, 2009 3:43 am 
Beginner
Beginner

Joined: Wed Feb 23, 2005 11:32 am
Posts: 25
Location: Austria/Vienna
in the hibernate config file add this:
Code:
      <property name="cache.use_second_level_cache">true</property>
      <property name="hibernate.cache.use_query_cache">true</property>
      <property name="hibernate.cache.provider_class">org.hibernate.cache.EhCacheProvider</property>


the provider class of course depends on the impl you decide.

for each cache provider you need an extra configuration.
for example an
Quote:
ehcache.xml
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kiran7881
 Post subject: Re: How setCacheable of Query will work
PostPosted: Tue May 12, 2009 6:06 am 
Beginner
Beginner

Joined: Wed May 06, 2009 12:23 pm
Posts: 23
Thank You very much cgs and nord.

I have cleared my query with Query Cache .

I have an another query also what if i use cache at Object level . Does this also require second level cache?
Code:
<class name="eg.Cat" .... >
    <cache usage="read-write"/>
    ....
    <set name="kittens" ... >
        <cache usage="read-write"/>
        ....
    </set>
</class>
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cgs
 Post subject: Re: How setCacheable of Query will work
PostPosted: Tue May 12, 2009 7:22 am 
Beginner
Beginner

Joined: Wed Feb 23, 2005 11:32 am
Posts: 25
Location: Austria/Vienna
yes, you do.

it is called association-caching

here also is an excellent article about caching:
http://www.javalobby.org/java/forums/m92235473.html

! Be careful with read-write caching. maybe you can start with read-only first.
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byto
 Post subject: Re: How setCacheable of Query will work
PostPosted: Tue May 12, 2009 9:36 am 
Newbie

Joined: Thu Nov 15, 2007 3:17 am
Posts: 19
cgs wrote:
! Be careful with read-write caching. maybe you can start with read-only first.

Can you please explain whats wrong with read-write? With read-only caching, Hibernate throws an exception on #saveOrUpdate(). So read-only doesnt seem very practically to me in most cases.
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cgs
 Post subject: Re: How setCacheable of Query will work
PostPosted: Tue May 12, 2009 10:07 am 
Beginner
Beginner

Joined: Wed Feb 23, 2005 11:32 am
Posts: 25
Location: Austria/Vienna
are you using casade insert and or update for kittens ?
what is the error you get exactly ?
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kiran7881
 Post subject: Re: How setCacheable of Query will work
PostPosted: Wed May 13, 2009 11:41 am 
Beginner
Beginner

Joined: Wed May 06, 2009 12:23 pm
Posts: 23
Quote:
! Be careful with read-write caching. maybe you can start with read-only first




<cache usage="read-write"/>

Whats danger with read-write ?


"On this my understanding with respect to above is that " Whenever there is a change of the entity at the database level the cache is also updated simultaneously " please tell me if i am right or wrong on this .

Waiting for your replies
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byto
 Post subject: Re: How setCacheable of Query will work
PostPosted: Thu May 14, 2009 3:01 am 
Newbie

Joined: Thu Nov 15, 2007 3:17 am
Posts: 19
kiran7881 wrote:
Whenever there is a change of the entity at the database level the cache is also updated simultaneously " please tell me if i am right or wrong on this .

IIRC the entity will be removed from cache when an UPDATE statement changes the cached entity. So the next Session#get() on the entity results in a CACHE MISS.
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kiran7881
 Post subject: Re: How setCacheable of Query will work
PostPosted: Sat May 16, 2009 11:00 am 
Beginner
Beginner

Joined: Wed May 06, 2009 12:23 pm
Posts: 23
Great Point byto , Can You then how to handle this type of situation ?
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