Need help with Hibernate? Read this first:
http://www.hibernate.org/ForumMailingli ... AskForHelp

Hibernate version: 3.0

Mapping documents:

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping>
<class name="entity.Address" table="address">


<id name="id" column="id" type="integer" access="field">
<generator class="increment"/>
</id>

<property
name="street"
column="street"
type="string"
access="field"/>
<property
name="apt"
column="apt"
type="string"
access="field"/>
<property
name="date"
column="date"
type="java.util.Date"
access="field"/>
<many-to-one
name="user"
column="user_id"
class="entity.User"
access="field"
lazy="false"
/>
</class>

</hibernate-mapping>

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping>
<class name="entity.User" table="user" >

<id name="id" column="id" type="integer" access="field">
<generator class="increment"/>
</id>

<property
name="name"
column="name"
type="string"
access="field"/>
<property
name="surname"
column="surname"
type="string"
access="field"/>
<property
name="pass"
column="pass"
type="string"
access="field"/>
<property
name="type"
column="type"
type="string"
access="field"/>

<set name="addresses" cascade="all" lazy="false" fetch="join" access="field">
<key column="user_id"/>
<one-to-many class="entity.Address"/>
</set>
</class>

</hibernate-mapping>


Code between sessionFactory.openSession() and session.close():

Full stack trace of any exception that occurs:

Name and version of the database you are using: MySql 4.0.15

The generated SQL (show_sql=true):

Debug level Hibernate log excerpt:

First of all i must say that i am new to hibernate.
I make two classes name User and Address and make biderectional relation between them.
in the database there are 100 users and for each of these users there are 1000 addresses (test code).

when i get the users (address also since non-lazy) like below

Session session = null;
Transaction tx = null;
session = HibernateSessionFactory.currentSession();
tx = session.beginTransaction();
Query query = session.createQuery( "from User" );
List list=null;
try{
list = query.list();
session.close();
}
catch(Exception ex){
ex.printStackTrace();
}

it takes too many times (nearly 10 seconds). what is wrong here.
Before sending this message i make a search on the forum but cannot solve the problem.

i couldnot solve this problem.
actually i dont know whether it is a problem or not.
i know there are some solutions like second-level cache.
but in my application, at some point i need to read these much of record (they arenot in the second-level cache) and it is to slow (5-6 time slower than jdbc)
is there any way to make these query faster?

still couldnot solve the problem
please help.

What's happening here is when you define fetchmode=join on the addresses, you end up joining both you user table and address table and the relationship is no longer lazy. If each user hase 10 addresses, you're getting back 10,000 User instances + addresses from your query. By removing the fetch mode, you'll see a dramatic speed improvement. Try turning on SQL logging so you can see what is happening:

http://www.hibernate.org/hib_docs/v3/re ... on-logging


The join fetchmode is most useful in a single-ended association, or if you use it to eagerly fetch a one-to-many association. Hope this helps.

Ryan-

thnx damnhandy.
before sending the first message i have also tried the no-fetch version you mentioned.
there is performance increase when i make it without fetch but it is still slow.

Try also setting a batch size on the user class, like batch-size="100". Do this in the class mapping. Also turn on SQL logging too, this will show what Hibernate is creating for a query and how it is executing the query. It will give you some insight as to why it is so slow.

Ryan-

One other thing to consider: if your running this query inside of a JUnit, make sure you account for Hibernate to build its configuration. This can take a fair amount of time depending on the number of mappings you have.

Ryan-