2 votes 2 votes Databases conflict-serializable view-serializable transaction-and-concurrency databases concurrency + – Parshu gate asked Dec 5, 2017 Parshu gate 982 views answer comment Share Follow See all 10 Comments See all 10 10 Comments reply Ashwin Kulkarni commented Dec 5, 2017 reply Follow Share It should be I and VI. is it? 0 votes 0 votes joshi_nitish commented Dec 5, 2017 reply Follow Share yes, correct. it is only view equivalent to T1->T2->T3 1 votes 1 votes saxena0612 commented Dec 5, 2017 reply Follow Share @joshi,@Aswani T2 is blindwriting and then value is read by T3 what difference will it make if i schedule w(a) before T2`s write(a) do i have to assume that T2 reading input or have read input previously? 0 votes 0 votes joshi_nitish commented Dec 5, 2017 reply Follow Share what difference will it make if i schedule w(a) before T2`s write(a) whose w(a) ?? 0 votes 0 votes saxena0612 commented Dec 6, 2017 reply Follow Share Transaction A write on (A). 0 votes 0 votes Parshu gate commented Dec 6, 2017 reply Follow Share why cant it be T2->T1->T3 ? 0 votes 0 votes joshi_nitish commented Dec 6, 2017 reply Follow Share @Parshu because if you do T2->T1->T3, then initial read R1(A) will not be preserved. 1 votes 1 votes saxena0612 commented Dec 6, 2017 reply Follow Share @joshi and what about T1->T2->T3? 0 votes 0 votes joshi_nitish commented Dec 6, 2017 reply Follow Share @saxena yes, T1->T2->T3 is only view equivalent to above schedule. 0 votes 0 votes srivivek95 commented Dec 6, 2017 reply Follow Share @ Parshu gate For this schedule T2->T1->T3 Yes T1 is reading the data item for the first time but it is not actually reading the value of the data item that was before the start of all the transactions as it will be overwritten by T2. So, this is not VS 1 votes 1 votes Please log in or register to add a comment.
0 votes 0 votes i and vi No cycle in polygraph and possible order is T1->T2->T3 according to the topological order of polygraph. Vishwesh Vinchurkar answered Jul 27, 2018 Vishwesh Vinchurkar comment Share Follow See all 0 reply Please log in or register to add a comment.