Spring, Hibernate, Blob lazy loading
- by Alexey Khudyakov
Dear Sirs,
I need help with lazy blob loading in Hibernate.
I have in my web application these servers and frameworks: MySQL, Tomcat, Spring and Hibernate.
The part of database config.
<bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource" destroy-method="close">
<property name="user" value="${jdbc.username}"/>
<property name="password" value="${jdbc.password}"/>
<property name="driverClass" value="${jdbc.driverClassName}"/>
<property name="jdbcUrl" value="${jdbc.url}"/>
<property name="initialPoolSize">
<value>${jdbc.initialPoolSize}</value>
</property>
<property name="minPoolSize">
<value>${jdbc.minPoolSize}</value>
</property>
<property name="maxPoolSize">
<value>${jdbc.maxPoolSize}</value>
</property>
<property name="acquireRetryAttempts">
<value>${jdbc.acquireRetryAttempts}</value>
</property>
<property name="acquireIncrement">
<value>${jdbc.acquireIncrement}</value>
</property>
<property name="idleConnectionTestPeriod">
<value>${jdbc.idleConnectionTestPeriod}</value>
</property>
<property name="maxIdleTime">
<value>${jdbc.maxIdleTime}</value>
</property>
<property name="maxConnectionAge">
<value>${jdbc.maxConnectionAge}</value>
</property>
<property name="preferredTestQuery">
<value>${jdbc.preferredTestQuery}</value>
</property>
<property name="testConnectionOnCheckin">
<value>${jdbc.testConnectionOnCheckin}</value>
</property>
</bean>
<bean id="lobHandler" class="org.springframework.jdbc.support.lob.DefaultLobHandler" />
<bean id="sessionFactory" class="org.springframework.orm.hibernate3.LocalSessionFactoryBean">
<property name="dataSource" ref="dataSource" />
<property name="configLocation" value="/WEB-INF/hibernate.cfg.xml" />
<property name="configurationClass" value="org.hibernate.cfg.AnnotationConfiguration" />
<property name="hibernateProperties">
<props>
<prop key="hibernate.dialect">${hibernate.dialect}</prop>
</props>
</property>
<property name="lobHandler" ref="lobHandler" />
</bean>
<tx:annotation-driven transaction-manager="txManager" />
<bean id="txManager" class="org.springframework.orm.hibernate3.HibernateTransactionManager">
<property name="sessionFactory" ref="sessionFactory" />
</bean>
The part of entity class
@Lob
@Basic(fetch=FetchType.LAZY)
@Column(name = "BlobField", columnDefinition = "LONGBLOB")
@Type(type = "org.springframework.orm.hibernate3.support.BlobByteArrayType")
private byte[] blobField;
The problem description. I'm trying to display on a web page database records related to files, which was saved in MySQL database. All works fine if a volume of data is small. But the volume of data is big I'm recieving an error "java.lang.OutOfMemoryError: Java heap space"
I've tried to write in blobFields null values on each row of table. In this case, application works fine, memory doesn't go out of. I have a conclusion that the blob field which is marked as lazy (@Basic(fetch=FetchType.LAZY)) isn't lazy, actually! How can I solve the issie?
Many thanks for advance.
