self-doubt

Question

During the questions of conflict serializability...which we solve by using the precedence graph....in that if transaction contains COMMIT or ABORT.....does any changes to do in precedence graph...or keep it as same as COMMIT and ABORT are not present...

so what will be answer of following ...????

Comments

I think precedence graph will be made excluding T2, the reason behind is if transaction is aborted the changes made by transaction is undone which means, that transaction will not have any effect.

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As far as serialisability of schedules is concerned , be it conflict serialisability or view serialisability , there we are not concerned about the commit/abort of the transactions..

For conflict serialisability , we check for conflict pairs irrespective of whether commit/abort is present or not..

It is recoverability of schedules where commit/abort comes into picture i.e. to check whether a schedule is recoverable or cascadeless rollback or strict schedule , we have to take commit/abort into consideration..

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For conflict serialisability , we check for conflict pairs irrespective of whether commit/abort is present or not..

@Habib sir,

i dont think it is true, consider the below schedule

 

here i think there is no WW conflict because T2 is finished before WW can occur, so it is conflict serilizable, if commits are ignored, it would not be conflict serilizable..