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Materialization

Steps in materialization between two operators
  • first operator reads input(s) and writes results to disk
  • next operator treats tuples on disk as its input
  • in essence, the Temp tables are produced as real tables
Advantage:
  • intermediate results can be placed in a file structure
    (which can be chosen to speed up execution of subsequent operators)
Disadvantage:
  • requires disk space/writes for intermediate results
  • requires disk access to read intermediate results