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Execution of Transactions (cont)

Operations available for data transfer:
  • INPUT(X) ... read page containing X into a buffer
  • READ(X,v) ... copy value of X from buffer to local var v
  • WRITE(X,v) ... copy value of local var v to X in buffer
  • OUTPUT(X) ... write buffer containing X to disk
READ/WRITE are issued by transaction.

INPUT/OUTPUT are issued by buffer manager (and log manager).

INPUT/OUTPUT correspond to getPage()/putPage() mentioned above