PIG bin/labeling relation

[drd_ <dh...@smartzip.com>]

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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Re: PIG bin/labeling relation

[Dmitriy Ryaboy <dv...@gmail.com>]

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.

-D

On Fri, Nov 20, 2009 at 1:18 PM, drd_ <dh...@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
> --
> View this message in context: http://old.nabble.com/PIG-bin-labeling-relation-tp26443615p26443615.html
> Sent from the Hadoop core-user mailing list archive at Nabble.com.
>
>