outOfMemory : cache configuration

will · **Joined:** Mon Aug 21, 2006 11:47 am **Posts:** 5

Hibernate version:3.1
Name and version of the database you are using:Oracle9i

Hi,

i'm working on a study for making a DOM cache over a relationnal database.
Database contains XML documents stored as subtrees.
Here is the main table :

Code:

CREATE TABLE XDB_ANCHORS
(
DOC_ID        NUMBER(10),
ID            NUMBER(10), //subtree id
PARENT_ID     NUMBER(10), // parent subtree id
POSITION  NUMBER(10), subtree position in the parent subtree
CONTENT       CLOB //XML
) 

CONTENT mapping is done using a UserType which takes the clob and creates a DOM.
So the transformation is done by hibernate and data are cached.

With small files it works fine, but with normal XML files (around 250Mb) I get an outOfMemory exception : Java Heap size.

Cached objects are never freed by session cache.
I used a profiler and I have no reference on my objects, there are only hibernate references.

I think that the problems comes from my cache configuration or maybe as i use UserType i have to evict the objects myself ?

Regards

William

mapping

Code:

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
        "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping>
   <class name="com.airbus.hdom.dom.AdocDocumentFragment" table="XDB_ANCHORS" mutable="false">
      <cache usage="read-only"/>
      <composite-id>
           <key-property name="docId" column="DOC_ID" type="int"/>
           <key-property name="id" type="int" column="ID"/>
           <key-property name="evo" type="int" column="EVO"/>
       </composite-id>
       
      <property name="parentId" column="PARENT_ID"/>
      <property name="key" column="KEY"/>
      <property name="isRemoved" column="ISREMOVED"/>
      <property name="startOffset" column="START_OFFSET"/>
      <property name="endOffset" column="END_OFFSET"/>
      <property name="root" type="com.airbus.hdom.util.HibernateTypes.ClobToDomType">
         <column name="CONTENT" sql-type="CLOB"/>
      </property>
    </class>
</hibernate-mapping> 

will · **Joined:** Mon Aug 21, 2006 11:47 am **Posts:** 5

i load objects from database using an oracle PIPELINED stored procedure.

so it returns a collection : is it possible to evict an object from the collection without evicting the entire collection ?

thanks

versoft · **Joined:** Wed Nov 22, 2006 5:09 pm **Posts:** 8

Hi Will,

I guess this is more of a question. Since you have used PIPELINED SP's. I have just started using them, Could you please let me know how to call them in the JAVA application. What are the necessary items required e.g mapping ect.

andresgr · **Posted:** Tue Nov 28, 2006 2:50 pm

Quote:

Cached objects are never freed by session cache

What do you mean? If you close() the session the objects are not freed?

What session/transaction strategy are you using?

Markus_Heiden · **Joined:** Sat May 14, 2005 11:19 am **Posts:** 14

Hibernate keeps a snapshot of all objects in the session until you close() it, clear() it or evict() the object. To avoid those snapshots you can setCacheMode(CacheMode.IGNORE) on your query or use a stateless session.