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From "Maryann Xue (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (PHOENIX-2198) Support correlate variable
Date Fri, 04 Sep 2015 03:18:45 GMT

    [ https://issues.apache.org/jira/browse/PHOENIX-2198?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14730254#comment-14730254
] 

Maryann Xue commented on PHOENIX-2198:
--------------------------------------

bq. Is it not currently possible to use the CorrelatedPlan in Phoenix, but only from the Calcite
branch?

Correct. In most cases, nested-loop join would have the worse performance, unless we know
in advance (from stats) that the outer relation is only going to produce a very limited number
of rows and executing the inner relation is cheap (for example a point lookup). So I think
this would only be worthwhile in Phoenix + Calcite, where we can cost it. CorrelatedPlan is
also used where correlated subqueries that cannot be de-correlated (not very common though),
and Phoenix does not have this front-end support yet. 

> Support correlate variable
> --------------------------
>
>                 Key: PHOENIX-2198
>                 URL: https://issues.apache.org/jira/browse/PHOENIX-2198
>             Project: Phoenix
>          Issue Type: New Feature
>            Reporter: Maryann Xue
>            Assignee: Maryann Xue
>         Attachments: PHOENIX-2198.patch
>
>   Original Estimate: 240h
>  Remaining Estimate: 240h
>
> This will enable the outer query to set a correlate variable as a parameter to restart
the inner query for each iteration.



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