Example: Strict 2PL

Questions

 * 1) Does the schedule on the right abide by the rules of 2PL?
 * 2) Does the schedule on the right abide by the rules of strict 2PL?

Answers

 * 1) The schedule follows 2PL because exclusive locks are acquired before writes and at least shared locks are acquired before reads. Also, locks are not requested after unlocking has begun

Questions

 * 1) Does this schedule on the right abide by the rules of 2PL?
 * 2) Does the schedule on the right abide by the rules of strict 2PL?

Answers

 * 1) The schedule follows 2PL because exclusive locks are acquired before writes and at least shared locks are acquired before reads. Also, locks are not requested after unlocking has begun
 * 2) The schedule does not follow? strict 2PL because not all of the unlocking is performed when the transaction is completed. Therefore, there is a possibility of cascading aborts