How to improve the performance?

ccsilva · **Joined:** Fri Nov 02, 2007 9:27 am **Posts:** 5

Hi,

I need of a suggestion to improve the performance of my code.

For example: I have two entities, User and Address. Each User has a Address attribute, as LAZY association. This model is ok, because only sometimes I need to read the Address from a User.

But in a screen of my system I need to simulate a EAGER. I used the Hibernate.initialize() and everything works fine (Below is my sample working code).

Code:

  
...
String str_query = "select u from User u";  
Query query = session.createQuery(str_query);  
List<User> list = query.list();  
  
for(User user: list){   
          Hibernate.initialize(user.getAddress());  
}  
  
return list;  
...

My doubt is: How to improve this code? Because, if I have 1000 Users and 1000 Addresses, the Hibernate will do 1001 SQLs (1 sql to list all users, and 1000 sqls to retrieve the addresses).

There are a way to tell to hibernate to do a single SQL to retrieve all required addresses?

Please, help me!

Thanks a lot!

Claudiney

typhos · **Joined:** Thu Mar 06, 2008 5:06 am **Posts:** 68

It should work this way:

Code:

  
...
String str_query = "from User u join fetch u.Address";  
Query query = session.createQuery(str_query);  
List<User> list = query.list();  
  
return list;  
...

satsranchuser · **Posted:** Wed May 07, 2008 9:46 am

If you have a lot of records, along with above suggestion u can set up a Hibernate Fetching strategy and get records as batches. As well Hibernate has good caching support.

http://www.devx.com/dbzone/Article/29685 is a decent one that can give some idea how to use secondary cache.

ccsilva · **Joined:** Fri Nov 02, 2007 9:27 am **Posts:** 5

typhos wrote:

It should work this way:

Code:

  
...
String str_query = "from User u join fetch u.Address";  
Query query = session.createQuery(str_query);  
List<User> list = query.list();  
  
return list;  
...

This way realy works fine, but now I have other problem:

Since that each Address has a State attribute defined as EAGER. The hibernate generates SQLs to retrieve each state.

is It possible increase more?

typhos · **Joined:** Thu Mar 06, 2008 5:06 am **Posts:** 68

I think, you can fetch it the same way:

Code:

String str_query = "from User u join fetch u.Address a join fetch a.State"; 
Query query = session.createQuery(str_query); 
List<User> list = query.list(); 
 
return list;

Try it out...

msj4u · **Joined:** Wed Apr 25, 2007 11:44 pm **Posts:** 59

typhos wrote:

I think, you can fetch it the same way:

Code:

String str_query = "from User u join fetch u.Address a join fetch a.State"; 
Query query = session.createQuery(str_query); 
List<User> list = query.list(); 
 
return list;

Try it out...

yes you are right this is doing the same thing in one