64 Large Scale and Big Data
experiments of the study show that the range index improves the perfor-
mance of MapReduce by a factor of 2 in the selection task and a factor of 10
in the join task when selectivity is high.
• There are two kinds of decoders for parsing the input records: mutable
decoders and immutable decoders. The study claims that only immutable
decoders introduce performance bottleneck. To handle database-like work-
loads, MapReduce users should strictly use mutable decoders. A mutable
decoder is faster than an immutable decoder by a factor of 10 and improves
the performance of selection by a factor of 2. Using a mutable decoder, even
parsing the text record is efcient.
• Map-side sorting exerts negative performance effect on ...