[infinispan-dev] [inifnispan-dev] MapReduce enhancement

[Ondra Nevelik]

No problem:) 
https://issues.jboss.org/browse/ISPN-1665
Thx!

----- Original Message -----
From: "Vladimir Blagojevic" <vblagoje at redhat.com>
To: "infinispan -Dev List" <infinispan-dev at lists.jboss.org>
Sent: Tuesday, January 3, 2012 1:33:50 PM
Subject: Re: [infinispan-dev] [inifnispan-dev] MapReduce enhancement

On 12-01-03 7:43 AM, Mircea Markus wrote:
> On 2 Jan 2012, at 16:49, Vladimir Blagojevic wrote:
>
>> Hi Ondra,
>>
>> On 12-01-02 9:40 AM, Ondra Nevelik wrote:
>>> Hi all,
>>> I was supposed to write an arbitrary app with Infinispan so I wanted to rewrite one of my programs that is implemented using Hadoop MapReduce to have a comparison of performance between the two.
>>>
>>> However the way MapReduce is done in Infinispan right now greatly limits the number of problems that can be solved with it - there is a reduce phase on local data on each of the compute nodes to decrease the amount of data transferred. There is a "global" reduce after that. This means that the types of input keys/values has to be the same as output types and that differs from the original MapReduce concept.
>> This is simply not true!
> Vladimir, I think Ondra refers to the fact that Reduce.reduce function consumes and returns the same type of objects: VOut [1]
> IIRC the reason behind this restrictive signature was to allow all sorts of internal optimisations, e.g. parallelising the reduce phase.
>
> [1] http://bit.ly/vO0GjY
>
>
Got it! Thanks Mircea and an apology Ondra! So the Collator 
http://bit.ly/t5fg7L does not help? Ok, lets implement combiner 
function! Ondra can you open a JIRA request?

Regards,
Vladimir
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