1 votes 1 votes How 2PL guarenteed serializability? I think conflict serializability is not guarenteed for 2PL. But may be view serializable Plz explain it Databases databases two-phase-locking-protocol transaction-and-concurrency + – srestha asked Jul 28, 2018 srestha 1.2k views answer comment Share Follow See all 5 Comments See all 5 5 Comments reply Show 2 previous comments Shaik Masthan commented Jul 28, 2018 reply Follow Share this not 2PL therefore it may or may not Conflict.... 0 votes 0 votes srestha commented Jul 28, 2018 reply Follow Share Plz tell me 1)Is it conflict serialzable or not? 2)why r u it is not 2PL? because, it has more than one growing and more than one shrinking phase?? 0 votes 0 votes Shaik Masthan commented Jul 28, 2018 reply Follow Share why it is not 2PL? in 2PL, there is no lock issued after one lock is released in same transaction... in your example, for T1, after releasing lock on Y, you are again acquiring lock on X, this Violates 2PL. Is it conflict serializable or not? There is loop exist btw T1 and T2 ===> it is not conflict serializable 0 votes 0 votes Please log in or register to add a comment.
4 votes 4 votes If a schedule is view then it must be guraenteed for serializability. if a schedule is conflict then it also a view . So its guraenteed for serilixability. But if a schedule is not conflict the. We can not say about view. So it may or may not be serializable . In 2PL it is guranteed of conflict schedule. Becz in 2PL schedule are in growing and shrinking phase. So precedence graph never contain cycle . If precedence graph have no cycle then it must be a conflict. If it is conflict then it is also view. Which is guranteed of serializability. 2PL is more strict then conflict. If a schedule is in conflict then it may or may not be in 2PL. But if schedule is in 2PL Then it must be guranteed of conflict. abhishekmehta4u answered Jul 28, 2018 abhishekmehta4u comment Share Follow See all 4 Comments See all 4 4 Comments reply srestha commented Jul 28, 2018 reply Follow Share if only view serializable, Can we say it serializable?? Say for r1(A) w2(A) commit2, w1(A) w3(A) commit3, commit1 what will be ur answer? 0 votes 0 votes abhishekmehta4u commented Jul 28, 2018 reply Follow Share Yes if a schedule is view then it guranted of serializable. 1 votes 1 votes srestha commented Jul 28, 2018 reply Follow Share try the upper example 0 votes 0 votes abhishekmehta4u commented Jul 28, 2018 reply Follow Share This schedule is view . So it is serializable 1 votes 1 votes Please log in or register to add a comment.