I read about UpdateTimestampsCache, QueryCache. But i want to be more clear about it.
Now i would like to understand how exactly cache is working.

I have one-to-many relation between Place & Person classes.
I am calling the below code twice in my test program to test performance which works good.
Each call loads Place and set of persons for the place. I am saving 400 milliseconds between calls.

-------------
query = session.getNamedQuery(findPlaceAndPeople); // see below for query
query.setCacheable(true);
query.setString("auctionId", auctionId);
resultList = query.list();
-------------


<hibernate-mapping>
<class name="com.peopleplacesmodel.model.Place" table="AUCTIONS">
<id name="ID" type="string" unsaved-value="null">
<column name="ID" sql-type="char(32)" not-null="true" />
<generator class="uuid.hex" />
</id>
<property name="NAME">
<column name="NAME" />
</property>
<property name="ADDR">
<column name="ADDR" />
</property>
<set name="person" lazy="true">
<key column="AUCTID" />
<one-to-many class="com.peopleplacesmodel.model.Person" />
</set>
</class>
<query name="findPlaceAndPeople">from Place as place where place.ID = :auctionId</query>
<query name="findPlaces">from Place as place</query>
</hibernate-mapping>

<hibernate-mapping>
<class name="com.peopleplacesmodel.model.Person" table="PRTDIRVIEW">
<composite-id name="personName" class="com.peopleplacesmodel.model.PersonPK">
<key-property name="AUCTID" />
<key-property name="PRTLNAME" />
<key-property name="PRTFNAME" />
</composite-id>
<property name="PHONE">
<column name="PHONE" />
</property>
</class>
</hibernate-mapping>

Hello. can someone talk about this pls

I'm sorry, what exactly is your question?

If you just want to know how the query cache "works", simply look at the sourcecode. Its quite straightforward.

Gavin,
Here is my question, may be with some additions to it.
Q1:
I had the following settings in my hibernate.properties.

hibernate.cache.use_query_cache true
hibernate.cache.provider_class net.sf.hibernate.cache.HashtableCacheProvider

and i am running the sql with 'query.setCacheable(true);' twice in loop to check the performace. I am assuming that my query results are cached since the response in the loop is faster the second time.

At this point i do not have "ehcache-0.6.jar" in my class path. Does this mean Cache is really working ? if so, using what type of cache ? I just some theoritical explanation.

Q2 :
Now i want to try EHCache too. Can you give me steps to set up EHCache ?

I just looked at ehcache.xml, could undestand to some extent.
I would like to set "maxElementsInMemory=1", overflowToDisk="true" and actually see the objects are written to disk.
I am looking for some example please.
Thanks

I wouldn't "assume" that. It could equally well be due to the fact that the second time the actual on-disk data is found in the operating system buffers, or that the DB itself is doing some caching.



You mentioned that you have configured hibernate to use HashtableCacheProvider, so I assume that Hibernate would thus use the built-in HashtableCache. AFAIK HashtableCache is basically a toy which shouldn't be used for other than testing purposes. You can check that the cache is actually working by putting the line



in your log4j.properties file and watching the log output.



Put ehcache-x.y.jar in the classpath, and configure the ehcache.xml file.



Then do that, if that is what you want to do. No need to ask for permission.



The ehcache website contains some documentation about how to set it up.