Spring with hibernate cache native query - spring

Question

I'm using Spring 3.2 with Hibernate 4. In my DAO implementation I want to cache the results of native SQL query. The method to get results of this query looks like this:
public List<Object[]> getBestSellers(String category)
{
Session session = sessionFactory.getCurrentSession();
Query query = session.createSQLQuery( "SELECT i_id, i_title, a_fname, a_lname , SUM(ol_qty) AS val " +
"FROM " +
"orders, order_line, item, author " +
"WHERE " +
"order_line.ol_o_id = orders.o_id AND item.i_id = order_line.ol_i_id " +
"AND item.i_subject = :category AND item.i_a_id = author.a_id GROUP BY i_id " +
"ORDER BY orders.o_date, val DESC" );
query.setParameter( "category", category );
query.setMaxResults( 50 );
query.setCacheable( true );
List<Object[]> res = query.list();
return res;
}
It seems like that doesn't work and I don't know why.
I have configured the Hibernate in applicationContext.xml like this:
<props>
<prop key="hibernate.jdbc.batch_size">50</prop>
<prop key="hibernate.show_sql">false</prop>
<prop key="hibernate.dialect">${jdbc.hibernate.dialect}</prop>
<prop key="hibernate.max_fetch_depth">4</prop>
<prop key="hibernate.cache.use_second_level_cache">true</prop>
<prop key="hibernate.cache.use_query_cache">true</prop>
<prop key="hibernate.cache.region.factory_class">org.hibernate.cache.ehcache.EhCacheRegionFactory</prop>
<prop key="hibernate.cache.provider_configuration_file_resource_path">classpath:ehcache.xml</prop>
<prop key="hibernate.generate_statistics">true</prop>
</props>
and my ehcache.xml:
<?xml version="1.0" encoding="UTF-8"?>
<ehcache xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:noNamespaceSchemaLocation="http://ehcache.org/ehcache.xsd">
<diskStore path="java.io.tmpdir/Cloudscale-cache"/>
<defaultCache
eternal="false"
maxElementsInMemory="1000"
overflowToDisk="false"
diskPersistent="false"
timeToIdleSeconds="0"
timeToLiveSeconds="600"
memoryStoreEvictionPolicy="LRU"
/>
<cache
name="org.hibernate.cache.spi.UpdateTimestampsCache"
maxElementsInMemory="50"
eternal="false"
timeToIdleSeconds="0"
timeToLiveSeconds="86400"
overflowToDisk="true"/>
<cache
name="org.hibernate.cache.internal.StandardQueryCache"
maxElementsInMemory="50"
eternal="false"
timeToIdleSeconds="0"
timeToLiveSeconds="86400"
overflowToDisk="true"/>
</ehcache>

Answer 1

if you want to cache native sql queries then you have to use addScalar()
by using addScalar() ;hibernate will try to converted result of sql query into return objects for individual named columns, rather than entities.
Modify your query as below
Query query = session.createSQLQuery( "SELECT i_id as a, i_title as b, a_fname as c, a_lname as d, SUM(ol_qty) AS val " +
"FROM " +
"orders, order_line, item, author " +
"WHERE " +
"order_line.ol_o_id = orders.o_id AND item.i_id = order_line.ol_i_id " +
"AND item.i_subject = :category AND item.i_a_id = author.a_id GROUP BY i_id " +
"ORDER BY orders.o_date, val DESC" ).addScalar("a").addScalar("b").addScalar("c").addScalar("d").addScalar("val");