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Insertion/Deletion with Sec.Index

Insertion:
  • each insert requires three files to be updated
  • potentially costly rearrangement of index files
Deletion:
  • use mark-style (tombstone) deletion for data tuples
  • Ix2 entries: can always mark as "deleted"
  • Ix1 entries: mark only after removing last instance for k in Ix2
  • periodic "vacuum" to reduce storage overhead if many deletions