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Mapping Rules

Aggregation operators (e.g. MAX, SUM, ...):
  • add as new operators in extended RA
    e.g. SELECT MAX(age) FROM ...    ⇒    max(Proj[age](...))
Sorting (ORDER BY):
  • add Sort operator into extended RA   (e.g. Sort[+name,-age](...))
Duplicate elimination (DISTINCT):
  • add Uniq operator into extended RA   (e.g. Uniq(Proj(...)))
Grouping (GROUP BY, HAVING):
  • add operators into extended RA   (e.g. GroupBy, GroupSelect )