Best way to get large number of objects by Id

thogau · **Joined:** Fri Aug 12, 2005 5:41 am **Posts:** 5

HI,

I need to retrieve a large collection of persistent objects having an array of primary keys (java.lang.Long).
Those objects are quite long to load and I was wondering what is the most efficient query to do that.
Thanks,

Thomas

frodeh · **Joined:** Wed Jan 19, 2005 6:07 am **Posts:** 20

You can use a query like this :

" from table where key in (?)"

and making the parameter a string of the complete list of keys you have

StringUtils.join(keyArray,",") (from the apache.commons-package).

This will load all objects with the keys in the key-array

sven · **Posted:** Fri Aug 12, 2005 6:57 am

frodeh wrote:

You can use a query like this :

" from table where key in (?)"

and making the parameter a string of the complete list of keys you have

StringUtils.join(keyArray,",") (from the apache.commons-package).

This will load all objects with the keys in the key-array

Taking the Jakarta Commons is redundant in this case.

Code:

Long[] keys = ...;
Query query = session.createQuery("select c from Class c where c.key in (:keys)");
query.setParameterList("keys", keys);

Best regards
Sven

thogau · **Joined:** Fri Aug 12, 2005 5:41 am **Posts:** 5

Thanks for your responses!
I tried Sven's solution and it works like a charm!

scesbron · **Joined:** Thu Sep 04, 2003 8:23 am **Posts:** 368

Be careful, in queries are limited to a certain number of values, this limit is dependant of your database.

sven · **Posted:** Fri Aug 12, 2005 8:18 am

thogau wrote:

Thanks for your responses!
I tried Sven's solution and it works like a charm!

You're welcome to rate answers helpful which helped solving your problem. :)

Best regards
Sven