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From "Maryann Xue (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (PHOENIX-852) Optimize child/parent foreign key joins
Date Tue, 26 Aug 2014 18:57:58 GMT

    [ https://issues.apache.org/jira/browse/PHOENIX-852?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14111140#comment-14111140
] 

Maryann Xue commented on PHOENIX-852:
-------------------------------------

With more than one qualified join key, like pkCol0 and pkCol1, what I'm trying to do is not
"where pkCol0 in ... and pkCol1 in ..." but instead "where (pkCol0, pkCol) in ...". These
two are different, and with the first where clause, there would be a lot of meaningless point
lookups. But I don't think RowValueConstructor can handle unordered key parts, like (pkCol1,
pkCol0). Am I right? 

> Optimize child/parent foreign key joins
> ---------------------------------------
>
>                 Key: PHOENIX-852
>                 URL: https://issues.apache.org/jira/browse/PHOENIX-852
>             Project: Phoenix
>          Issue Type: Improvement
>            Reporter: James Taylor
>            Assignee: Maryann Xue
>         Attachments: 852-2.patch, 852.patch, PHOENIX-852.patch
>
>
> Often times a join will occur from a child to a parent. Our current algorithm would do
a full scan of one side or the other. We can do much better than that if the HashCache contains
the PK (or even part of the PK) from the table being joined to. In these cases, we should
drive the second scan through a skip scan on the server side.



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