Week 09 (45)

45

Schedules (cont)

Serial schedules guarantee database consistency

each T_i commits before T_i+1
prior to T_i database is consistent
after T_i database is consistent (assuming T_i is correct)
before T_i+1 database is consistent ...

Concurrent schedules interleave tx operations arbitrarily

and may produce a database that is not consistent
after all of the transactions have committed successfully