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https://issues.apache.org/jira/browse/FLINK-838?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14090564#comment-14090564
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Artem Tsikiridis commented on FLINK-838:
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Hi Fabian,
wow! That's a very deep change and the tests pass, it's great!
This was initially my plan for the key comparator... And then i did it by
modifying the {{WritableComparator}} and adding a hook in {{WritableTypeInfo}}
because I realised I had to go into the execution stack. Of course, for the
grouping comparator this would be impossible. So it is inevitable to go deep
like you did in this branch (and not with naive {{IdentityReduce}} functions
between partitioning and grouping)!
The same key comparator and sorting are used for the combiner in Hadoop.
However, in Hadoop 2.x (only), a custom grouping comparator can be used for
combiners with {{JobConf.setCombinerKeyGroupingComparator}}. I've been trying
to do it in the last hours. Should I submit a PR to your repo ?
Again, the branch is very cool, probably the most proper way! Many thanks.
> GSoC Summer Project: Implement full Hadoop Compatibility Layer for
> Stratosphere
> -------------------------------------------------------------------------------
>
> Key: FLINK-838
> URL: https://issues.apache.org/jira/browse/FLINK-838
> Project: Flink
> Issue Type: Improvement
> Reporter: GitHub Import
> Labels: github-import
> Fix For: pre-apache
>
>
> This is a meta issue for tracking @atsikiridis progress with implementing a
> full Hadoop Compatibliltiy Layer for Stratosphere.
> Some documentation can be found in the Wiki:
> https://github.com/stratosphere/stratosphere/wiki/%5BGSoC-14%5D-A-Hadoop-abstraction-layer-for-Stratosphere-(Project-Map-and-Notes)
> As well as the project proposal:
> https://github.com/stratosphere/stratosphere/wiki/GSoC-2014-Project-Proposal-Draft-by-Artem-Tsikiridis
> Most importantly, there is the following **schedule**:
> *19 May - 27 June (Midterm)*
> 1) Work on the Hadoop tasks, their Context and the mapping of Hadoop's
> Configuration to the one of Stratosphere. By successfully bridging the Hadoop
> tasks with Stratosphere, we already cover the most basic Hadoop Jobs. This
> can be determined by running some popular Hadoop examples on Stratosphere
> (e.g. WordCount, k-means, join) (4 - 5 weeks)
> 2) Understand how the running of these jobs works (e.g. command line
> interface) for the wrapper. Implement how will the user run them. (1 - 2
> weeks).
> *27 June - 11 August*
> 1) Continue wrapping more "advanced" Hadoop Interfaces (Comparators,
> Partitioners, Distributed Cache etc.) There are quite a few interfaces and it
> will be a challenge to support all of them. (5 full weeks)
> 2) Profiling of the application and optimizations (if applicable)
> *11 August - 18 August*
> Write documentation on code, write a README with care and add more
> unit-tests. (1 week)
> ---------------- Imported from GitHub ----------------
> Url: https://github.com/stratosphere/stratosphere/issues/838
> Created by: [rmetzger|https://github.com/rmetzger]
> Labels: core, enhancement, parent-for-major-feature,
> Milestone: Release 0.7 (unplanned)
> Created at: Tue May 20 10:11:34 CEST 2014
> State: open
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