Aggregation & Duplicate Removal (cont.)

• Hashing

  • Hash on group attributes
  • Can perform aggregation/duplicate removal when creating hash table

• Algorithm analysis

  • Sorting and hashing functions are logaritmic with input size

Previous slide

Next slide

Back to first slide

View graphic version

Cost:

Hashing- based on the number of partitioning levels required before the output of one partition fits into memory.