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

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