self doubt

Question

what is the difference between basic , conservative , strict and rigorous lock ?

Comments

conservative = take all required lock before start

strict = release all exclusive lock after commit or abort

rigorous lock = take all  release after commit or abort

Answer 1

Basic: locking can be done only  at growing phase and unlocking at shrinking phase.  deadlock and cascading rollback possible.

Strict: Exclusive locks should be held until transaction commits + basic 2PL. Strict. Cascade less but deadlock problem.

Rigorous lock:  all locks should be held until transaction commits + basic 2PL. Strict. Cascade less but deadlock problem.

Conservative : Locks should be acquired before transaction start and should be held until transaction commits +  + basic 2PL. free from deadlock.

Comments

well here you have only applied the locks but have not done anything from it...in this case it will be strict...

but if you have performed any read or right operation from it then it will be not strict...

because in strict neither you can read nor  write  from an  uncommitted data...

you should also see a difference between cascadless and strict schedule ..

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Can u give me an example of strrict and rigorous where there is deadlock ?

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your definition of conservative 2pl is not correct for correct deff go here conservative two phase locking protocol