Incorect Input to Reduce

Jonathan Langevin jlangevin at loomlearning.com
Wed Nov 30 10:01:32 EST 2011


The reduce phase receives data in batches. Per the docs, the default size
is for every 20 inputs, reduce.
The batch size can be tuned via config or per m/r request.

Re: 13, likely what you're seeing is the length of the last phase sent to
reduce. It seems if I return [values.length], I get just the last set that
processed, whereas returning [values] gives me all results concatenated.
I'd expect that I'd get length concatenated multiple times, but I must not
be formatting the response properly.

Regarding tuning (batch size):
http://wiki.basho.com/MapReduce.html#Configuration-Tuning-for-Reduce-Phases

 <http://www.loomlearning.com/>
* Jonathan Langevin
Manager, Information Technology
Loom Inc.
Wilmington, NC: (910) 241-0433 - jlangevin at loomlearning.com -
www.loomlearning.com - Skype: intel352 *



On Wed, Nov 30, 2011 at 9:03 AM, Yehuda Zargrov <Yehuda at conduit.com> wrote:

> Hi,****
>
> ** **
>
> I’ve posted a mail on this few days ago, but went a bit further since then.
> ****
>
> ** **
>
> I’m using ripple, running a map function on some input and getting a list
> of about 50 items.****
>
> ** **
>
> Right after that, I’m running a reduce function. The first thing I do in
> it is putting the length of v (the input) as an item in a list.****
>
> ** **
>
> When printing the result I see that the length is 13.****
>
> ** **
>
> It’s like something has happened between the map and reduce phases.****
>
> ** **
>
> Any ideas?****
>
> ** **
>
>   ****
>
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>
> *Yehuda Zargrov**
> *Software Engineer****
>
> *Conduit Your Site* <http://www.conduit.com/>****
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