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From Robert Metzger <rmetz...@apache.org>
Subject Fwd: [stratosphere-dev] Grouping by a tuple
Date Wed, 11 Jun 2014 22:25:06 GMT
Hi Slava,

I'm forwarding your message to our new mailing list at Apache:
You can subscribe to the list by sending an (empty) email to:
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:
So you should be able to do a ".groupBy(0,3,4)"


---------- Forwarded message ----------
From: Vyacheslav Zholudev <vyacheslav.zholudev@gmail.com>
Date: Thu, Jun 12, 2014 at 12:17 AM
Subject: [stratosphere-dev] Grouping by a tuple
To: stratosphere-dev@googlegroups.com


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

Or am I missing the obvious way in a Stratosphere way?


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