[
https://issues.apache.org/jira/browse/TAJO-903?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14056034#comment-14056034
]
ASF GitHub Bot commented on TAJO-903:
-------------------------------------
Github user hyunsik commented on the pull request:
https://github.com/apache/tajo/pull/56#issuecomment-48448719
+1
The patch looks good to me. It includes enough unit tests to verify added
features. In addition, I added some of explanation to the source code. I'll
commit it shortly.
> Left outer join should be optimized by the broadcast join.
> ----------------------------------------------------------
>
> Key: TAJO-903
> URL: https://issues.apache.org/jira/browse/TAJO-903
> Project: Tajo
> Issue Type: Improvement
> Reporter: Hyoungjun Kim
> Assignee: Hyoungjun Kim
> Priority: Minor
>
> The next query has three small tables and expected broadcast join, but not.
> {code:sql}
> select count(*) from large1
> left outer join large2 on large1_id = large2_id
> left outer join small1 on large1_id = small1_id
> left outer join small2 on large1_id = small2_id
> left outer join small3 on large1_id = small3_id
> {code}
> The next is the upper query's plan.
> {noformat}
> |-eb_1404411535695_0000_000011
> |-eb_1404411535695_0000_000010
> |-eb_1404411535695_0000_000009 (join)
> |-eb_1404411535695_0000_000008 (small)
> |-eb_1404411535695_0000_000007 (join)
> |-eb_1404411535695_0000_000006 (small)
> |-eb_1404411535695_0000_000005 (join)
> |-eb_1404411535695_0000_000004 (small)
> |-eb_1404411535695_0000_000003 (join)
> |-eb_1404411535695_0000_000002 (large)
> |-eb_1404411535695_0000_000001 (large)
> {noformat}
> Optimized plan should be the next.
> {noformat}
> |-eb_1404411906426_0000_000005
> |-eb_1404411906426_0000_000004
> |-eb_1404411906426_0000_000003 (broadcast small1, small2, small3)
> |-eb_1404411906426_0000_000002 (large)
> |-eb_1404411906426_0000_000001 (large)
> {noformat}
--
This message was sent by Atlassian JIRA
(v6.2#6252)
