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Varieties of Selection

Selection:   select * from R where C
  • filters a subset of tuples from one relation R
  • based on a condition C on the attribute values
We consider three distinct styles of selection:
  • 1-d (one dimensional)   (condition uses only 1 attribute)
  • n-d (multi-dimensional)   (condition uses >1 attribute)
  • similarity   (approximate matching, with ranking)
Each style has several possible file-structures/techniques.