JDO Query Performance

[Bastian Breithaupt <ba...@web.de>]

Hello!

I have a table with some 6000 rows and I have to make a query to select some 20 rows. I have read this thread:
http://www.mail-archive.com/ojb-user@db.apache.org/msg00626.html
from the ojb-user list, which says, that first all rows of a tabel are read into memory (in my understanding...)

In fact, my query takes quite a while to be finished (3-5 secs); this is my code:

manager = factory.getPersistenceManager();
manager.currentTransaction().begin();
Extent extent = manager.getExtent( Class.forName( myClass ) , true);
query = manager.newQuery( extent , filter );
result = (Collection)query.execute();
manager.currentTransaction().commit();

Any hints on how to build a fatser query with ojb and jdo?

Thanks a lot for your help

Bastian
______________________________________________________________________________
Erdbeben im Iran: Zehntausende Kinder brauchen Hilfe. UNICEF hilft den
Kindern - helfen Sie mit! https://www.unicef.de/spe/spe_03.php


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Re: JDO Query Performance

[Gus Heck <gu...@olin.edu>]

>
> SO all you can do for the moment is to wait for our own full JDO 
> implementation that will not have such limitations.
>
So when does this start? Will it use the current JDO related classes or 
rewrite them? I might be interested in pitching in, a bit when it does 
if I can find a small chunk or two to work on. (I probably can't do a 
whole lot of work, but it would be fun to help to some extent).

-Gus


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Re: JDO Query Performance

[Thomas Mahler <th...@web.de>]

Hi Bastian,

Your understanding of that other message is correct.
As the JDORI plugin mechanism does not provide any abstraction of 
performing selections.
This is a deficit of SUN's JDORI and not of OJB!
The bad news is that there is no way to get around this problem.

SO all you can do for the moment is to wait for our own full JDO 
implementation that will not have such limitations.

cheers,
thomas

Bastian Breithaupt wrote:
> Hello!
> 
> I have a table with some 6000 rows and I have to make a query to select some 20 rows. I have read this thread:
> http://www.mail-archive.com/ojb-user@db.apache.org/msg00626.html
> from the ojb-user list, which says, that first all rows of a tabel are read into memory (in my understanding...)
> 
> In fact, my query takes quite a while to be finished (3-5 secs); this is my code:
> 
> manager = factory.getPersistenceManager();
> manager.currentTransaction().begin();
> Extent extent = manager.getExtent( Class.forName( myClass ) , true);
> query = manager.newQuery( extent , filter );
> result = (Collection)query.execute();
> manager.currentTransaction().commit();
> 
> Any hints on how to build a fatser query with ojb and jdo?
> 
> Thanks a lot for your help
> 
> Bastian
> ______________________________________________________________________________
> Erdbeben im Iran: Zehntausende Kinder brauchen Hilfe. UNICEF hilft den
> Kindern - helfen Sie mit! https://www.unicef.de/spe/spe_03.php
> 
> 
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: ojb-user-unsubscribe@db.apache.org
> For additional commands, e-mail: ojb-user-help@db.apache.org
> 
> 


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