Hi,

Sorry I am a newbie w.r.t hibernate and I need some help in understanding how to define natural-id for my table.

My database structure is as follows

provisionId auto-increment (pk)
name varchar(255) not null
dept varchar(255) not null
D , E, F some other fields..

(name,dept) Unique

My queries are lookups based on (name,dept).

I am trying to use hibernate query caching to cache my queries so I don't have to go to the database all the time. From what I read online, for query cache to be effective, I want to define a natural-id which referes to a unique row in the table and as long as the natural-id doesn't change, any updates to a row will not result in invalidation of my query cache. So I can update (id,D,E,F) and when I query with (A,B) the value should come from cache.

In order to do this in my hibernate config file, I have

<cache usage="read-write"/>
<id name="provisionId" type="int" column="provision_id" unsaved-value="null">
<generator class="native" />
</id>
<natural-id>
<property name="name" type="java.lang.String"
column="name" length="255" />
<property name="dept" type="java.lang.String"
column="dept" length="255" />
</natural-id>

When I do the query I use

crit.add(Restrictions.naturalId().set("name", name));
crit.add(Restrictions.naturalId().set("dept", dept));
crit.setCacheable(true);
return crit.uniqueResult();


This works for the tests I have done. Do you see any issues with this?

My next issue is I want to add a new column maildrop to my existing table such that (name,maildrop) is unique. I would also want to query based on (name,maildrop) and I want it to work same as (name,dept) with respect to query cache.

Can someone tell me how do i add this to my xml file? If I add to the <natural-id> block wont it become unique(name,dept,maildrop) which is not what I want.

I would appreciate if you could give me any pointers... Thanks.

No, I don't see any issues with this.
The unique thing to notice is, that since Hibernate4.1 the NaturalId feature has become a big enhancement,
for example you don't need to use the second level query cache anymore,
see http://in.relation.to/Bloggers/41FeatureLoadingByNaturalId



You can do that, but not with the NaturalId feature.
You cannot define multiple sets of NaturlalId's for a single entity class or a class hierarchy (HHH-7129).