Optimized loading.
From what I read in the manual the "on_find" will load me all the matched records,
which may be a lot or even to much,
therefore there is the "on_load" which only loads the "page_size" specified number of records.
But in all the examples the "on_find" also has the "<page_size>" tag so now I am lost.
Is this tag superfluous in case of "on_find" or are there other differences.
Is there a different meaning for "on_find" and "on_load" when specified by a ejbfindBy or ejbSelect, and in a relation?
Where to specify the read ahead tags on 1..n relations in order to:
Load the fields of the related entity bean when accessing the getter from the 1 side.
Loading all the entities (and eventually some of there field data) when accessing the getter from the n side.
What do I have to specify where?
Here is an example which may (hopefully) clarify my question
I used XDoclet tags and the resulting xml is at the end.
In an Entity Bean (called Leaf) there is a method to retrieve the links from this Leaf
/**
*
* @ejb.interface-method
* view-type = "local"
*
* @ejb.relation
* name = "fromLeaf-linkFroms"
* role-name = "LeafLinkFromsRelationshipRole"
*
* @jboss.relation-read-ahead
* strategy = "on-find"
* eager-load-group = "allFields"
*/
public abstract java.util.Collection getLinkFroms();
The Link class the related to Leaf contains the corresponding method
/**
*
* @ejb.interface-method
* view-type = "local"
*
* @ejb.relation
* name = "fromLeaf-linkFroms"
* role-name = "LinkFromLeafRelationshipRole"
*
* @jboss.relation
* fk-column = "FROMLEAF_PKLEAFID"
* related-pk-field = "pkLeafId"
*
* @jboss.load-group
* name = "allFields"
*
* @jboss.relation-read-ahead
* strategy = "on-find"
* page-size = "1000"
* eager-load-group = "allFields"
*/
public abstract com.ascom.opentas.as.element.internal.entitybeans.Leaf getFromLeaf();
In my jbosscmp-jdbc.xml file the corresponding entry looks like
<ejb-relation>
<ejb-relation-name>fromLeaf-linkFroms</ejb-relation-name>
<ejb-relationship-role>
<ejb-relationship-role-name>LinkFromLeafRelationshipRole</ejb-relationship-role-name>
<key-fields/>
<read-ahead>
on-find
<page-size>1000</page-size>
<eager-load-group>allFields</eager-load-group>
</read-ahead>
</ejb-relationship-role>
<ejb-relationship-role>
<ejb-relationship-role-name>LeafLinkFromsRelationshipRole</ejb-relationship-role-name>
<key-fields>
<key-field>
<field-name>pkLeafId</field-name>
<column-name>FROMLEAF_PKLEAFID</column-name>
</key-field>
</key-fields>
<read-ahead>
on-find
<eager-load-group>allFields</eager-load-group>
</read-ahead>
</ejb-relationship-role>
</ejb-relation>
We currently are using jboss-3.2.6RC2 (with JRE 1.4.2_07) together with Oracle9i as DB
Many many thanks for any help, information or suggestion to a person in distress.
Percy Christian
