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https://issues.apache.org/jira/browse/TAJO-850?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14009665#comment-14009665
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Hyoungjun Kim commented on TAJO-850:
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I found the following documents for the OUTER JOIN's filter push down.
http://www.ibm.com/developerworks/data/library/techarticle/purcell/0112purcell.html
https://cwiki.apache.org/confluence/display/Hive/OuterJoinBehavior
There are many logic to fix fully outer join capability, so I will fix only for
filters in WHERE clause in this issues.
I'll create other ISSUE for OUTER JOIN's ON clause push down.
> OUTER JOIN does not properly handle a NULL.
> -------------------------------------------
>
> Key: TAJO-850
> URL: https://issues.apache.org/jira/browse/TAJO-850
> Project: Tajo
> Issue Type: Bug
> Reporter: Hyoungjun Kim
> Assignee: Hyoungjun Kim
> Priority: Minor
>
> See the title. In the case of the following query NULL value is evaluated at
> the SCAN time.
> {code:sql}
> select
> c_custkey,
> coalesce(orders.o_totalprice, 999.0)
> from
> customer left outer join orders on c_name = o_orderstatus
> {code}
> {code:sql}
> select
> c_custkey,
> from
> customer left outer join orders on c_name = o_orderstatus
> where o_orderdate is null
> {code}
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