3.6.10. Traversal

  • Traversal of graph
    • (aka. positive closure)
    • gives intermediate relation
  • Goal
    • Intermediate relation minimisation
      • Space (memory, disk triangle)
      • Time (fast joins versus slow joins)
        • Fewer relations
        • Fewer active attributes (horizontal cropping)
        • Fewer rows (vertical cropping)
          • Role of single-relation WHERE statements