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From Dmitriy Ryaboy <dvrya...@gmail.com>
Subject Re: PIG bin/labeling relation
Date Sat, 21 Nov 2009 20:04:11 GMT
Unless you actually need the ordinal numbers, you can do it all in one step:
B = ORDER A by x PARALLEL 100;
Store B into ......

This will create 100 ordered part files, with the first part file
containing the first 100th of the data, the second -- the next 100th,
and so on. The fragments are approximate in size, so some may be
slightly bigger than others, but for a big enough dataset, they should
be roughly equal.


On Fri, Nov 20, 2009 at 1:18 PM, drd_ <dharmendra@smartzip.com> wrote:
> I am using PIG and this is what I am trying to do:
> 1) Sort a relation A into B by a field x. The smallest value of x is first.
> Just use SORT.
> 2) Label each tuple in B with a number denoting its order in the sorted
> relation. So the first tuple would be labeled with a 1, the second tuple
> with a 2, the third with a 3 and so on. Not certain how to do this.
> 3) Derive a relation C where each row is a bag of tuples. The first row
> contains the first n1 tuples from relation B, the second row contains the
> tuples from B labeled (n1 + 1) to n2 from, the third row contains the tuples
> from B labeled (n2 + 1) to n3 and so on to n100. This step is simple (just
> use filter) once we've labeled each tuple in B with a number.
> The question: how do I do step 2).
> thanks
> --
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