Shevek, The problem Mathias indicates here is that the Combiners do not utilize the Grouping Comparators. They only use the Sort Comparators. Is that probably a bug is what I wonder.
On 31-Oct-2011, at 11:14 PM, Shevek wrote: > 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. >>
