Post by Admin on Mar 13, 2014 14:37:49 GMT
a)Partitioner allows you to distribute how outputs from tha map storage are sent to the reducers basically it pasctictions the key space.
b)Partitioner controls the partitioning the keys of the inter mediate map-outputs the key [subset of the key ] is used to derive the partition
c)Partitioner run on the same machine after mapper had completion ,by consuming mapper
o/p had completed its executing by consuming mapper 0\p so entire mapper output (record) is
sent to practitioner and practitioner forms (no-of record task) groups from the mapper output.
d)By default hand framework hash based practitioner this particular practitioner the key space by using the has code .
e)The following is logic hash practitioner executes to determine a reducer for a particular ‘key’ (key – hash code() & integer. MAX –VALUE )%num reduce tasks.