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https://issues.apache.org/jira/browse/FLINK-1591?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14342464#comment-14342464
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ASF GitHub Bot commented on FLINK-1591:
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GitHub user gyfora opened a pull request:
https://github.com/apache/flink/pull/444
[FLINK-1591] Removed unnecessary merge before flatten as optimisation
This PR adds an optimisation to the WindowingOptimizer which will remove
the unnecessary merge operation on the streamwindows before the flatten calls.
This adds major performance improvement since the flatten call now can be
easily chained to the windowing transformations and also eliminates the need of
an expensive merge transformation
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/mbalassi/flink FLINK-1591
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/flink/pull/444.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #444
----
commit 606909b714dd20386d3cdaf9bd94e5d01318a3ea
Author: Gyula Fora <[email protected]>
Date: 2015-03-01T21:09:55Z
[FLINK-1591] [streaming] Removed unnecessary merge before flatten as
optimisation
----
> Remove window merge before flatten as an optimization
> -----------------------------------------------------
>
> Key: FLINK-1591
> URL: https://issues.apache.org/jira/browse/FLINK-1591
> Project: Flink
> Issue Type: Improvement
> Components: Streaming
> Reporter: Gyula Fora
> Assignee: Gyula Fora
>
> After a Window Reduce or Map transformation there is always a merge step when
> the transformation was parallel or grouped.
> This merge step should be removed when the windowing operator is followed by
> flatten to avoid unnecessary bottlenecks in the program.
> This feature should be added as an optimization step to the
> WindowingOptimizer class.
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