2.2.16b. Query optimisation implementation

  • Indexing accelerates query resolution
  • Closed comparison (intra-tuple)
    • all variables/attributes within single tuple
    • e.g. x < 100
  • Open comparison (inter-tuple)
    • variables span multiple tuples
  • Essentially a sorting problem
  • Internal sorting covered (pre-requisites)
  • Need external sort for non-cached lists