[hibernate-issues] [Hibernate-JIRA] Updated: (HHH-4924) Unnecessary "left outer join". Probably this "left outer join" can be eliminated. OneToOne when optional=true and LAZY

[Adam Wozniak (JIRA)]

     [ http://opensource.atlassian.com/projects/hibernate/browse/HHH-4924?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Adam Wozniak updated HHH-4924:
------------------------------

    Attachment: PersonPk.java
                Person.java
                Office.java

> Unnecessary "left outer join". Probably this "left outer join" can be eliminated. OneToOne when optional=true and LAZY
> ----------------------------------------------------------------------------------------------------------------------
>
>                 Key: HHH-4924
>                 URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-4924
>             Project: Hibernate Core
>          Issue Type: Improvement
>          Components: core
>    Affects Versions: 3.3.1
>         Environment: n/a
>            Reporter: Adam Wozniak
>         Attachments: CREATE TABLES POSTGRESQL.sql, Office.java, Person.java, PersonPk.java
>
>
> Hi
> Relation between Person and Office is: 1 to {0 or 1}
> There a 3 classes (sources attached):
> * PersonPk
> * Person
> * Office
> SCENARIO
> --------
> 	final Office office = em.find(Office.class, new PersonPk("adam", "woz"));
> 	System.out.println(office.getPerson().getZodiac());
> I second line the following SQL is generated:
> select
>         person0_.first_name as first1_22_1_,
>         person0_.last_name as last2_22_1_,
>         person0_.zodiac as zodiac22_1_,
>         office1_.first_name as first1_23_0_,
>         office1_.last_name as last2_23_0_,
>         office1_.address as address23_0_ 
>     from
>         PERSON person0_ 
>     left outer join
>         OFFICE office1_ 
>             on person0_.first_name=office1_.first_name 
>             and person0_.last_name=office1_.last_name 
>     where
>         person0_.first_name=? 
>         and person0_.last_name=?
> But we already know all columns for OFFICE so there is need to loaded them once again. In other words this SQL can be reduced to such SQL:
> select
>         person0_.first_name as first1_22_1_,
>         person0_.last_name as last2_22_1_,
>         person0_.zodiac as zodiac22_1_,
>     from
>         PERSON person0_ 
>     where
>         person0_.first_name=? 
>         and person0_.last_name=?
> Kind regards,
> Adam Woźniak / Poland

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