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From "Stephan Ewen (JIRA)" <j...@apache.org>
Subject [jira] [Resolved] (FLINK-1214) Prevent partitioning pushdown unless partitions fields match exactly
Date Thu, 06 Nov 2014 13:02:33 GMT

     [ https://issues.apache.org/jira/browse/FLINK-1214?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Stephan Ewen resolved FLINK-1214.
---------------------------------
    Resolution: Fixed

Fixed in 6ecd0f8264ab5cfb6101046a415c996993b682e5

> Prevent partitioning pushdown unless partitions fields match exactly
> --------------------------------------------------------------------
>
>                 Key: FLINK-1214
>                 URL: https://issues.apache.org/jira/browse/FLINK-1214
>             Project: Flink
>          Issue Type: Bug
>          Components: Optimizer
>    Affects Versions: 0.8-incubating
>            Reporter: Stephan Ewen
>            Assignee: Stephan Ewen
>             Fix For: 0.8-incubating
>
>
> Consider an operation grouped on fields (A, B), followed by an operation grouped on field
(A).
> Right now, the optimizer can push down the partitioning on (A), which serves both operations
(the first step locally still groups by A and B). This may however by a bad idea for the cases
where the field A has a low cardinality, or the value distribution is skewed.
> Since we cannot determine that robustly yet, I suggest to disable this optimization for
now.



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