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From "James Taylor (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (PHOENIX-852) Optimize child/parent foreign key joins
Date Thu, 14 Aug 2014 22:33:20 GMT

    [ https://issues.apache.org/jira/browse/PHOENIX-852?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14097820#comment-14097820
] 

James Taylor commented on PHOENIX-852:
--------------------------------------

Yes, that's the code. +1 for new JIRA. We allow this slotSpan array to be passed through to
the skip scan now. If we have a case like WHERE (c0, c1) IN ((?,?),(?,?)), then the row keys
will span two slots instead of one. So in this case the slotSpan array would be [1], as it
defines the number of columns that the row key covers minus one.

> 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
>
> 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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