
49MapReduce Family of Large-Scale Data-Processing Systems
recursively, select data partitions based on query conditions, and feed only selected
partitions to other primitives.
The map–join–reduce [76] represents another approach that has been introduced
with a ltering–join–aggregation programming model as an extension of the standard
MapReduce’s ltering–aggregation programming model. In particular, in addition to
the standard mapper and reducer operation of the standard MapReduce framework,
they introduce a third operation, join (called joiner), to the framework. Hence, to join
multiple data sets for aggregation, users specify a set of join ...