I like the ability to reuse a Java component for both sorting and grouping, and to be honest, since the cases where one can do a comparison without deserializing the raw bytes are relatively few and far between, I tend to use java's Comparator interface, and wrap it in some infrastructure-specific adapter. I have a vague feeling that Hadoop sometimes calls the byte interface and sometimes the object interface anyway? ICBW, the way I've been writing code makes it irrelevant.
Alternatively, I've misunderstood the (simpler) question, and the answer is to use the setGroupingComparatorClass() API. S. On 29 October 2011 04:35, Mathias Herberts <[email protected]>wrote: > Another point concerning the Combiners, > > the grouping is currently done using the RawComparator used for > sorting the Mapper's output. Wouldn't it be useful to be able to set a > custom CombinerGroupingComparatorClass? > > Mathias. >
