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Modified Multiversion Locking

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intregrisist Posts: 41	Posted 15:14 Dec 07, 2010 \| Basing this off Q.5 in the sample final. Can we say something like: T1: w1(b1), w1(b2) T2: w2(b2) T3: r3(b1), r3(b2) w1(b1), w1(b2), c1, r3(b1), w2(b2), c2, r3(b2), c3 If we check serializability it fails since T3 reads the b1 from transaction 1 and b2 from transaction 2. Is this a valid answer? If not, can you please explain on how to show that it can produce a non-serializable schedule? I watched the video lecture but you're working off the camera so I can't see. Last edited by intregrisist at 15:39 Dec 07, 2010.
cysun Posts: 2935	Posted 15:54 Dec 07, 2010 \| That's not a valid answer because it's perfectly serializable. I don't give out answers to the sample exams. You need to figure it out or discuss with others. Last edited by cysun at 15:55 Dec 07, 2010.

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intregrisist

Posts: 41

Posted 15:14 Dec 07, 2010 |

Basing this off Q.5 in the sample final. Can we say something like:

T1: w1(b1), w1(b2)
T2: w2(b2)
T3: r3(b1), r3(b2)

w1(b1), w1(b2), c1, r3(b1), w2(b2), c2, r3(b2), c3

If we check serializability it fails since T3 reads the b1 from transaction 1 and b2 from transaction 2. Is this a valid answer? If not, can you please explain on how to show that it can produce a non-serializable schedule? I watched the video lecture but you're working off the camera so I can't see.

Last edited by intregrisist at 15:39 Dec 07, 2010.

cysun

Posts: 2935

Posted 15:54 Dec 07, 2010 |

That's not a valid answer because it's perfectly serializable.

I don't give out answers to the sample exams. You need to figure it out or discuss with others.

Last edited by cysun at 15:55 Dec 07, 2010.