Strict Two-Phase Locking

• Strict two-phase locking:

  • A transaction cannot write into the database until it has reached its commit point.
  • A transaction cannot release any locks until it has finished writing into the database; therefore locks are not released until after the commit point.

• pros:

  • transaction read only values of committed transactions
  • no cascaded aborts

• cons:

  • limited concurrency
  • deadlocks

• Models/protocols can be extended for READ/WRITE locks.

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