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https://issues.apache.org/jira/browse/OPENJPA-547?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Catalina Wei closed OPENJPA-547.
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Resolution: Fixed
> INNER JOIN Fetch query incorrectly generates LEFT join SQL
> -----------------------------------------------------------
>
> Key: OPENJPA-547
> URL: https://issues.apache.org/jira/browse/OPENJPA-547
> Project: OpenJPA
> Issue Type: Bug
> Components: query
> Reporter: Catalina Wei
> Assignee: Catalina Wei
> Fix For: 1.0.3, 1.1.0
>
>
> INNER JOIN FETCH should not generate SQL LEFT join.
> Example:
> lineitems (ToMany, FetchType=LAZY)
> Order <===================================> OrderItem
> order (ToOne, FetchType=LAZY)
> For Query: select o from Order left join fetch o.lineitems
> SQL generated
> for DB2:
> SELECT t0.oid, t0.version, t0.amount, t0.delivered, t1.ORDER_OID, t1.lid,
> t1.version, t1.cost, t1.quantity
> FROM TORDER t0 LEFT OUTER JOIN TORDERITEM t1 ON t0.oid = t1.ORDER_OID ORDER
> BY t1.ORDER_OID ASC
> for Oracle:
> SELECT t0.oid, t0.version, t0.amount, t0.delivered, t1.ORDER_OID, t1.lid,
> t1.version, t1.cost, t1.quantity FROM TORDER t0, TORDERITEM t1 WHERE t0.oid =
> t1.ORDER_OID(+) ORDER BY t1.ORDER_OID ASC
> The above SQL pushdown looked good.
> However, if left join fetch is changed to inner join fetch:
> select o from Order o inner join fetch o.lineitems
> We are generating extra redundant LEFT joins:
> for DB2:
> SELECT t0.oid, t0.version, t0.amount, t0.delivered, t2.ORDER_OID, t2.lid,
> t2.version, t2.cost, t2.quantity
> FROM TORDER t0 INNER JOIN TORDERITEM t1 ON t0.oid = t1.ORDER_OID LEFT OUTER
> JOIN TORDERITEM t2 ON t0.oid = t2.ORDER_OID ORDER BY t2.ORDER_OID ASC
> for Oracle:
> SELECT t0.oid, t0.version, t0.amount, t0.delivered, t2.ORDER_OID, t2.lid,
> t2.version, t2.cost, t2.quantity FROM TORDER t0, TORDERITEM t1, TORDERITEM t2
> WHERE t0.oid = t1.ORDER_OID AND t0.oid = t2.ORDER_OID(+) ORDER BY
> t2.ORDER_OID ASC
> Why do we generate the extra LEFT joins even for quereis explicitly
> requesting INNER join fetch ?
>
>
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