Hello,
I'have a problem.
I have read online that id generator increment is not thread safe.
For this i have some problem in my servlet based application.
Sometimes i have exception for duplicate id if two thread work.
I use Oracle...for kill any problem what id generator i can use that work very well with oracle?
Native?Sequence?
Help me.
Thank you.
N.B.:Sorry for my english.

CIAO A TUTTI!

I'd recommend the hilo generator

http://hibernate.org/hib_docs/reference ... on-id-hilo

it's thread and cluster safe while being fast and database independent

Use a sequence or if you want some database independence use native (which equals sequence in Oracle).

I read...

<generator class="net.sf.hibernate.id.TableHiLoGenerator">
<param name="table">uid_table</param>
<param name="column">next_hi_value_column</param>
</generator>

I must ubsert one table for each entity?

Or 1 tabel for all entity?

thank's!

You can use a different table for each object if you want, but it's not required.

If you use the same table the ID's will be unique across all types (which can be useful in itself.

You can actually just do the following and let hibernate default the table and column names.



If you do want the id's to be generated separately for each type, you can either use hilo configured with a different table for each type, or the MultipleHiLoPerTableGenerator:

http://www.hibernate.org/hib_docs/v3/ap ... rator.html

You also have the option of the Sequence HiLo Generator. This works like a hilo but uses a Sequence to get the hi bits rather than a table holding the next id.
http://www.hibernate.org/hib_docs/v3/ap ... rator.html



As for using the sequence generator. I know in hibernate 2 it was badly implemented which resulted in a serious performance hit. I haven't checked if this has been fixed in hibernate 3.