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https://issues.apache.org/jira/browse/FLINK-2549?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14902262#comment-14902262
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ASF GitHub Bot commented on FLINK-2549:
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GitHub user ChengXiangLi opened a pull request:
https://github.com/apache/flink/pull/1161
[FLINK-2549] add topK operator to DataSet.
The topK operator is implemented with `mapPartition()` followed by
`reduceGroup()`, each map tasks select top k elements, and transfer to
singleton reduce task(no `group()` before `reduceGroup()`), and then select top
k elements in reduce task.
The main part of this implementation:
1. An out-of-core self managed memory based PriorityQueue implementation.
2. Use runtime resources to build PriorityQueue for UDF. topK is not real
'native' operator actually, it contains UDF which use self managed memory based
PriorityQueue to select top k elements.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/ChengXiangLi/flink priorityqueue
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/flink/pull/1161.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 #1161
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commit 7165d5ba78376cec1b3c752afb949e6273d45869
Author: chengxiang li <[email protected]>
Date: 2015-09-16T02:10:05Z
[FLINK-2549] add topK operator to DataSet.
----
> Add topK operator for DataSet
> -----------------------------
>
> Key: FLINK-2549
> URL: https://issues.apache.org/jira/browse/FLINK-2549
> Project: Flink
> Issue Type: New Feature
> Components: Core, Java API, Scala API
> Reporter: Chengxiang Li
> Assignee: Chengxiang Li
> Priority: Minor
>
> topK is a common operation for user, it would be great to have it in Flink.
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