[jboss-user] [EJB3] - Hibernate HQL optimization

csab79 [http://community.jboss.org/people/csab79] created the discussion "Hibernate HQL optimization" To view the discussion, visit: http://community.jboss.org/message/585768#585768 -------------------------------------------------------------- hello Hibernate gurus! I would like to improve my app performance through HQL optimzation. I have a small example to show my problem: <?xml version="1.0"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" " http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"> <hibernate-mapping>     <class name="hibernate.classes.Peoples" table="PEOPLES" catalog="Dev1">             <id name="PId" type="int">                 <column name="P_ID" />                 <generator class="identity"/>             </id>             <property name="pfirstname" type="string">                 <column name="p_firstname" />             </property>             <property name="plastname" type="string">                 <column name="p_lastname" />             </property>             <property name="phobby" type="string">                 <column name="p_hobby" />             </property>           <many-to-one name="address" class="hibernate.classes.Address" fetch="join" insert="false" update="false">                       <column name="p_adress" not-null="true"/>                   </many-to-one> </class> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" " http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"> <hibernate-mapping>     <class name="hibernate.classes.Address" table="ADDRESS" catalog="Dev1">             <id name="AId" type="int">                 <column name="A_ID" />                 <generator class="identity"/>             </id>             <property name="street" type="string">                 <column name="a_street" />             </property>             <property name="house" type="string">                 <column name="a_house" />             </property>             <property name="district" type="string">                 <column name="a_district" />             </property> </class> I'd like to display rows from people and also show the appropriate person's address (foreign key bind) When i use HQL join like this way: session.createQuery("from  Peoples inner join Address") I suppose in this case .tolist() does not work properly becouse there are additional join properties. When i use simple ("from Peopes") HQL query together with many-to-one default lazy="proxy" the result will be terrible slow. Hibernate try to gets seperatly every row from Address with foreign key selects. (May is it the N+1 Select problem?) This is an impact when i have many rows in my table. What is the best practice when i always want to display this cross joined datas?  (pfirstname, plastname, phobby, street, house) Should i use iterator and manually place each property from the query result? Thanks in advance! Sorry for the dummy question! :S   -------------------------------------------------------------- Reply to this message by going to Community [http://community.jboss.org/message/585768#585768] Start a new discussion in EJB3 at Community [http://community.jboss.org/choose-container!input.jspa?contentType=1&...]