Application of Filters to Multiway Joins in MapReduce

Algorithm 2

Converting a coordinate to a reducer id.

(1) procedure  COORDTOREDUCER(𝑐𝑜𝑜𝑟𝑑[1,…,𝑛],𝑟𝑒𝑝𝑙[1,…,𝑛])

(2)  𝑟𝑒𝑑𝑢𝑐𝑒𝑟←0

(3)  𝑏𝑎𝑠𝑒←1

(4)  for  𝑖=1 to 𝑛  do

(5)   𝑟𝑒𝑑𝑢𝑐𝑒𝑟←𝑟𝑒𝑑𝑢𝑐𝑒𝑟+𝑏𝑎𝑠𝑒∗𝑐𝑜𝑜𝑟𝑑[𝑖]

(6)   𝑏𝑎𝑠𝑒←𝑏𝑎𝑠𝑒∗𝑟𝑒𝑝𝑙[𝑖]

(7)  end for

(8)  return  𝑟𝑒𝑑𝑢𝑐𝑒𝑟

(9) end procedure