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From "Maryann Xue (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (PHOENIX-852) Optimize child/parent foreign key joins
Date Mon, 01 Sep 2014 17:01:20 GMT

    [ https://issues.apache.org/jira/browse/PHOENIX-852?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14117560#comment-14117560
] 

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

Think the getSampleValue() itself has no problem, plus it also provides two other signatures
as "getSampleValue(maxLength, arrayLength)" and "getSampleValue(maxLength)", in which "maxLength"
is only useful for VARCHAR, CHAR, VARBINARY, BINARY and their corresponding array types, and
if not specified we'll just give a default value "1". I just need to adjust my PDataTypeTest.testGetSampleValue()
to use the "toObject()" method with parameter "maxLength".


> 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, 852-3.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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