In this tutorial, we'll learn how to cache results that are
fetched from the Query object.
Session session = sessionFactory.openSession();
session.beginTransaction();
Query query = session.createQuery("from UserDetails user where user.userId = 1");
query.setCacheable(true);
List users = query.list();
session.getTransaction().commit();
session.close();
Session session2 = sessionFactory.openSession();
session2.beginTransaction();
Query query2 = session2.createQuery("from UserDetails user where user.userId = 1");
query2.setCacheable(true);
users = query2.list();
session2.getTransaction().commit();
session2.close();
Above code run two select quries, to overcome this we need to write query cache property.
<property name="cache.use_query_cache">true</property>
In order to make query cachable we need to tell hibernate to cache using below statement.
query.setCacheable(true);
HibernateTest.java
package org.yash.hibernate;
import java.util.List;
import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
public class HibernateTest {
public static void main(String
args[]) {
SessionFactory
sessionFactory = new Configuration().configure().buildSessionFactory();
Session session =
sessionFactory.openSession();
session.beginTransaction();
Query query =
session.createQuery("from
UserDetails user where user.userId = 1");
query.setCacheable(true);
List users = query.list();
session.getTransaction().commit();
session.close();
Session session2
= sessionFactory.openSession();
session2.beginTransaction();
Query query2 =
session2.createQuery("from
UserDetails user where user.userId = 1");
query2.setCacheable(true);
users = query2.list();
session2.getTransaction().commit();
session2.close();
}
}
UserDetails.java
package org.yash.dto;
import java.util.ArrayList;
import java.util.Collection;
import javax.persistence.Cacheable;
import javax.persistence.CascadeType;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.NamedQuery;
import javax.persistence.OneToMany;
import org.hibernate.annotations.Cache;
import org.hibernate.annotations.CacheConcurrencyStrategy;
@Entity
@Cacheable
@Cache(usage=CacheConcurrencyStrategy.READ_WRITE)
@NamedQuery(name="UserDetails.byId", query="from
UserDetails where userId = ?") //HQL query - based on class name
@org.hibernate.annotations.Entity(selectBeforeUpdate=true)
public class UserDetails {
/* @Id says
"userId" is primary key */
@Id @GeneratedValue
(strategy=GenerationType.AUTO)
private int userId;
private String userName;
@OneToMany(cascade=CascadeType.PERSIST)
private
Collection<Vehicle> vehicle = new
ArrayList<Vehicle>();
public int getUserId() {
return userId;
}
public void setUserId(int userId) {
this.userId = userId;
}
public String
getUserName() {
return userName;
}
public void
setUserName(String userName) {
this.userName = userName;
}
public void
setVehicle(Collection<Vehicle> vehicle) {
this.vehicle = vehicle;
}
public
Collection<Vehicle> getVehicle() {
return vehicle;
}
}
hibernate.cfg.xml
<?xml
version='1.0' encoding='utf-8'?>
<!DOCTYPE
hibernate-configuration PUBLIC
"-//Hibernate/Hibernate
Configuration DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
<session-factory>
<property name="connection.driver_class">
org.postgresql.Driver
</property>
<property name="connection.url">
jdbc:postgresql://localhost:5433/hibernatedb
</property>
<property name="connection.username">postgres</property>
<property name="connection.password">admin</property>
<!-- JDBC
connection pool (use the built-in) -->
<property name="connection.pool_size">1</property>
<!-- SQL
dialect -->
<property name="dialect">
org.hibernate.dialect.PostgreSQLDialect
</property>
<!-- Second level cache provider -->
<property name="cache.use_second_level_cache">true</property>
<property name="cache.use_query_cache">true</property>
<property name="hibernate.cache.region.factory_class">
org.hibernate.cache.ehcache.EhCacheRegionFactory
</property>
<!-- Enable
Hibernate's automatic session context management -->
<property name="current_session_context_class">thread</property>
<!-- Echo
all executed SQL to stdout -->
<property name="show_sql">true</property>
<!-- Drop
and re-create the database schema on startup -->
<property name="hbm2ddl.auto">update</property>
<!-- create / update -->
<!-- Names the annotated entity
class -->
<mapping class="org.yash.dto.UserDetails"/>
<mapping class="org.yash.dto.Vehicle"/>
<mapping class="org.yash.dto.TwoWheeler"/>
<mapping class="org.yash.dto.FourWheeler"/>
</session-factory>
