Pardon, what I said is not completely right. Both functions are incrementally constructed. This seems obvious for the reduce function but is also true for the GroupReduce because it receives the values as an Iterable which, under the hood, can be constructed incrementally as well.
One other difference is that the traditional reduce always applies a combiner before shuffling the results. The GroupReduceFunction, on the other hand, does not do that unless you explicitly specify a combiner using the RichGroupReduceFunction or perform a GroupCombine operation before the GroupReduce. Best regards, Max On Fri, May 22, 2015 at 10:03 AM, Maximilian Michels <m...@apache.org> wrote: > Like you said, it depends on the use case. The GroupReduceFunction is a > generalization of the traditional reduce. Thus, it is more powerful. > However, it is also executed differently; a GroupReduceFunction requires > the whole group to be materialized and passed at once. If your program > doesn't require that, use the normal reduce function. > > On Thu, May 21, 2015 at 4:42 PM, santosh_rajaguru <sani...@gmail.com> > wrote: > >> i am new to flink and map reduce. My query is >> Apart from incrementally combing 2 elements, what are the merits of using >> reduceFunction over GroupReduceFunction. which usecases suits what >> functions >> the most!!! >> >> >> >> >> >> >> -- >> View this message in context: >> http://apache-flink-mailing-list-archive.1008284.n3.nabble.com/difference-between-reducefunction-and-GroupReduceFunction-tp5768.html >> Sent from the Apache Flink Mailing List archive. mailing list archive at >> Nabble.com. >> > >
