[hibernate-issues] [Hibernate-JIRA] Created: (HHH-6042) To much columns in select queries after creating criteria with join
To much columns in select queries after creating criteria with join
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Key: HHH-6042
URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-6042
Project: Hibernate Core
Issue Type: Bug
Components: core
Affects Versions: 3.2.6
Environment: <dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate</artifactId>
<version>3.2.6.ga</version>
</dependency>
Any database
Reporter: Karol Kowalczyk
Attachments: AbstractEntityJoinWalker.java, Loader.java
When I create criteria for any class with any value of property of association f.e.:
java code:
eventDCriteria = DetachedCriteria.forClass(Event.class);
personDCriteria = eventDCriteria.createCriteria("participants");
personDCriteria.add(Expression.eq("age", 41));
List<Event>
events=(List<Event>)getHibernateTemplate().findByCriteria(eventDCriteria, 0, 2);
class mappings:
<class name="Event" table="EVENTS">
<id name="id" column="EVENT_ID">
<generator class="native"/>
</id>
<property name="date" type="timestamp"
column="EVENT_DATE"/>
<property name="title"/>
<set name="participants" table="PERSON_EVENT"
inverse="true">
<key column="EVENT_ID"/>
<many-to-many column="PERSON_ID" class="Person"/>
</set>
</class>
<class name="Person" table="PERSON">
<id name="id" column="PERSON_ID">
<generator class="native"/>
</id>
<property name="age"/>
<property name="firstname"/>
<property name="lastname"/>
<set name="events" table="PERSON_EVENT" >
<key column="PERSON_ID"/>
<many-to-many column="EVENT_ID" class="Event"/>
</set>
<set name="emailAddresses" table="PERSON_EMAIL_ADDR" >
<key column="PERSON_ID"/>
<element type="string" column="EMAIL_ADDR"/>
</set>
</class>
a Hibernate still creates select query f.e.:
select e.EVENT_ID, e.EVENT_DATE, e.title, pe.EVENT_ID, pe.PERSON_ID, p.PERSON_ID, p.age,
p.firstname, ...
from EVENTS e
inner join PERSON_EVENT pe on pe.EVENT_ID=e.EVENT_ID
inner join PERSON p on p.PERSON_ID=pe.PERSON_ID
where p.age=?;
Why this hibernates query have UNNECESSARY list of columns: pe.EVENT_ID, pe.PERSON_ID,
p.PERSON_ID, p.age, p.firstname, ...?
This query is not INDEXONLY for any databases.
More EFFECTIVE query is:
select e.EVENT_ID, e.EVENT_DATE, e.title
from EVENTS e
inner join PERSON_EVENT pe on pe.EVENT_ID=e.EVENT_ID
inner join PERSON p on p.PERSON_ID=pe.PERSON_ID
where p.age=?;
A prepared only for my two changes in hibernate: Loader.java and
AbstractEntityJoinWalker.java to get more effective selects.
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