one-to-one property-ref and 2'nd level cache

dorel · **Joined:** Thu Jun 10, 2004 6:52 am **Posts:** 29

Hibernate version:3.1.2

I've put this problem long ago (h 2.1.8) and I don't know if there is a solution to it or not.

I have a bidirectional one-to-one A-B relationship through property-ref (FK, I cannot model it through shared PK way (or can I ?) because A can have a B or not, they can live and have a meaning separately). The problem is that it doesn't work with the 2'nd level cache. When listing no matter what As or Bs, I get a select for the property-ref for each item in the list while I'd expect to get it from the cache.

Is there a solution to this ? I'm sorry I've looked all around the forums and found only unclear or "not implemented" responses.

Please see this

http://forum.hibernate.org/viewtopic.ph ... yref+cache

for the other post.

Thanks.

tenwit · **Joined:** Thu Dec 23, 2004 9:08 pm **Posts:** 2008

dorel wrote:

I have a bidirectional one-to-one A-B relationship through property-ref (FK, I cannot model it through shared PK way (or can I ?) because A can have a B or not, they can live and have a meaning separately).

You can have a PK-to-PK zero-or-one-to-zero-or-one bidirectional mapping by specifying it as many-to-one unique="true" in both directions.

The reason your cache (and most significantly, your session cache: the 2nd level cache is less important for this sort of thing) isn't getting hit is probably down to using a foreign key at one end. I'm not sure, but switching to many-to-one on PKs should improve cache hits.

dorel · **Joined:** Thu Jun 10, 2004 6:52 am **Posts:** 29

tenwit wrote:

You can have a PK-to-PK zero-or-one-to-zero-or-one bidirectional mapping by specifying it as many-to-one unique="true" in both directions.

Brilliant. It works. I'll rate.