Aggregation & Duplicate Removal (cont.)

• Similarities

  • Algorithms require grouping
  • Algorithms based on sorting

• Differences

  • Comparison of attributes
  • Treatment of duplicate items

• Treated as the same in this paper

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Comparison of attributes:

Dup. Removal- all

Aggregation- only on attributes in the by-list of aggrefate functions

Duplicate items:

Dup. Removal- immediately dropped

Aggregation- some calculation done before dropping