On the cluster running the Hadoop and MapReduce setup, we can consider that these key
value pairs are sent to the machine in which the reducer process operates.
FIGURE 4.12 Sorting of key value pairs
M
M
M
Split 1ABACB
CBBBBAAAAADCCCCCCD
DD
DCADC
Split 2
Split 3
Now, these key value pairs are sorted such that all values which have the same key are available
together and are then fed to the reducer. The sorting implies that all prole views for a particular
member, say John, are available in a group.
FIGURE 4.13 Reducer function applied to sorted results
M
M
R
M
Split 1ABACB
CBBBBAAAAADCCCCCCDDD
ABCD
DCADC
Split 2
Split 3
The reducer ...
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