Posted by
Robert Metzger on
Jun 11, 2014; 10:25pm
URL: http://deprecated-apache-flink-mailing-list-archive.368.s1.nabble.com/Fwd-stratosphere-dev-Grouping-by-a-tuple-tp40.html
Hi Slava,
I'm forwarding your message to our new mailing list at Apache:
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We are planning to shut down the stratosphere-dev@googlegroups soon.
Regarding your question: When using the Tuples, you don't need to specify a
keySelector. It is sufficient to specify the ID(s) of the keys:
http://stratosphere-javadocs.github.io/eu/stratosphere/api/java/DataSet.html#groupBy(int..
.)
So you should be able to do a ".groupBy(0,3,4)"
Robert
---------- Forwarded message ----------
From: Vyacheslav Zholudev <
[hidden email]>
Date: Thu, Jun 12, 2014 at 12:17 AM
Subject: [stratosphere-dev] Grouping by a tuple
To:
[hidden email]
Hi,
Being used to the Hive grouping like "GROUP BY userId, productId, year" I'm
wondering what's the best way to do it in Stratosphere? The groupBy's
KeySelector implies that a Comparable object is returned, however, the
obvious choice like TupleN is not comparable. In primitive cases I would
prefer to avoid introducing comparable extra entities for grouping tuples
of "primitive" types. Would it make sense to introduce "ComparableTupleN<T1
extends Comparable<? extends T1>, ..., Tn extends Comparable<? extends
Tn>>"?
Or am I missing the obvious way in a Stratosphere way?
Thanks,
Vyacheslav
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