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Posted to issues@flink.apache.org by "Gabor Gevay (JIRA)" <ji...@apache.org> on 2015/06/03 11:52:49 UTC

[jira] [Updated] (FLINK-2145) Median calculation for windows

     [ https://issues.apache.org/jira/browse/FLINK-2145?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Gabor Gevay updated FLINK-2145:
-------------------------------
    Labels: statistics  (was: )

> Median calculation for windows
> ------------------------------
>
>                 Key: FLINK-2145
>                 URL: https://issues.apache.org/jira/browse/FLINK-2145
>             Project: Flink
>          Issue Type: Sub-task
>          Components: Streaming
>            Reporter: Gabor Gevay
>            Assignee: Gabor Gevay
>            Priority: Minor
>              Labels: statistics
>
> The PreReducer for this has the following algorithm: We maintain two multisets (as, for example, balanced binary search trees), that always partition the elements of the current window to smaller-than-median and larger-than-median elements. At each store and evict, we can maintain this invariant with only O(1) multiset operations.



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