Fields API: Reduce Functions of GroupBuilder¶
com.twitter.scalding.GroupBuilder
mapStream¶
Full access to the Iterator of values. Avoid it if you can as this cannot be optimized much
scanLeft¶
A particular, but common, pattern to processes an iterator and return a new iterator.
foldLeft¶
Exactly like the above, but we only keep the last value.
reduce / mapReduceMap¶
Preferred operations, which are partially executed on the mappers.