Hibernate2

I have only just started using hibernate and am experiencing very large number of hits on the database when I am trying to query just one table.

For each Service issue it finds within the query it runs two sub queries to get the region codes and the products which are both one to many.

I do not want to use these objects and do not want the overhead of an extra 2 queries for each record that my original query brings back. I have tried lazy loading as can be seen below but am not sure if I am applying it correctly or if it is the right thing to do.

Regards

Stephen

Mapping documents:

<?xml version="1.0"?>

<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 2.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd">

<hibernate-mapping>
<class
name="com.company.servicestatus.bo.ServiceIssue"
table="service_issue"
dynamic-update="false"
dynamic-insert="false"
>

<id
name="ticketNo"
column="se_ticket_no"
type="int"
>
<generator class="native">
</generator>
</id>

<set
name="regionCodes"
lazy="true"
inverse="false"
cascade="none"
sort="unsorted"
>

<key
column="ticket_no"
/>

<one-to-many
class="com.company.servicestatus.bo.IssueRegionCode"
/>
</set>

<set
name="products"
lazy="true"
inverse="false"
cascade="none"
sort="unsorted"
>

<key
column="ticket_no"
/>

<one-to-many
class="com.company.servicestatus.bo.IssueProduct"
/>
</set>

<property
name="timestamp"
type="timestamp"
update="true"
insert="true"
column="se_timestamp"
/>

<property
name="name"
type="string"
update="true"
insert="true"
column="se_name"
/>

<property
name="department"
type="string"
update="true"
insert="true"
column="se_department"
/>

<property
name="briefDescription"
type="string"
update="true"
insert="true"
column="se_brief_descr"
/>

<property
name="detailDescriptionCLOB"
type="clob"
update="true"
insert="true"
column="se_detail_descr"
/>

<property
name="customerAffected"
type="string"
update="true"
insert="true"
column="se_cust_affected"
/>

<property
name="estimatedTime"
type="string"
update="true"
insert="true"
column="se_est_time"
/>

<property
name="priority"
type="string"
update="true"
insert="true"
column="se_priority"
/>

<property
name="status"
type="string"
update="true"
insert="true"
column="se_status"
/>

<property
name="modifiedTimestamp"
type="timestamp"
update="true"
insert="true"
column="se_mod_timestamp"
/>

<!--
To add non XDoclet property mappings, create a file named
hibernate-properties-ServiceIssue.xml
containing the additional properties and place it in your merge dir.
-->

</class>

</hibernate-mapping>



Database: Oracle 8i

map the following classes: com.company.servicestatus.bo.IssueRegionCode and com.company.servicestatus.bo.IssueProduct with lazy="true"
e.g:

this is usefull for to-one relationship...

in this case twogun seems to have well written his mapping files.

show hql query and check if you have something on the setters. If something tries to hit the collections, then the other queries are executed.

Yes, I am wrong... missed set with one-to-many. In that case set should be lazy-initialized.

Thanks Anthony and shl,

on looking at the setter methods in the DTO they were loading the two sets causing my problem.


Regards


Stephen

don't forget to test "fetch" keyword, you'll need it later