Hello everybody

I am Bert and I am part of the team of weewar.com a turn based strategy game.

In advance: Hibernate is great. I want to thank the developers and the open source community for creating such a great product.

My problem concerns a cached collections. I am using a second level cache (ehcache). All essential mapping documents can be found below.

Here is my problem:

My application loads an object of class "EventCollection" that contains a cached collection that consists of objects of class "Event". The contents of this collection is loaded using the fetch="join" attribute once the EventCollection is loaded. Hence all this is done with one single sql query.

I can now access the EventCollection and the containing Events as I like and no futher sql queryies are made.

Everything works fine until Events expire from the second level cache. If I access the events after that each Event is loaded with one sql statement.

Thanks a lot

Bert

Hibernate version: 3.1.3

Mapping documents:

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd" >
<hibernate-mapping package="com.weewar.model">
<class
name="EventCollection"
table="EventCollection"
>
<meta attribute="sync-DAO">true</meta>
<cache usage="read-write"/>
<id
name="Id"
type="integer"
column="collection_id"
>
<generator class="native"/>
</id>

<list name="events" fetch="join" lazy="false">
<key column="collection_id" />
<list-index column="position" />
<one-to-many class="Event" />
</list>

</class>

<class
name="Event"
table="Event"
batch-size="300"
>
<meta attribute="sync-DAO">true</meta>
<cache usage="read-write"/>
<id
name="Id"
type="integer"
column="event_id"
>
<generator class="native"/>
</id>

<property
name="timestamp"
column="timestamp"
type="timestamp"
/>

<property
name="position"
column="position"
type="int"
length="11"
/>
<many-to-one
name="eventCollection"
column="collection_id"
class="EventCollection"
/>
<many-to-one
name="player"
column="player_id"
class="Player"
/>

<!-- ommitted lots of properties here -->

</class>
</hibernate-mapping>

hibernate.cfg.xml contains the following entry:

<collection-cache collection="com.weewar.model.EventCollection.events" usage="read-write"/>



Name and version of the database you are using:

MySql 5.0

Read this: http://hibernate.org/42.html

Good morning. I am still working on this. Right now I have enlarged the cache size of the Event Objects to guarantee that Events will never expire before the EventCollection Objects. It looks as if this makes the thing work but still it feels more like a work arround and I am curious if there are "real" solutions to this problem