Figures (a) and (b) show two independent sequences of reads and writes for data items in a distributed DB across various
Posted: Sun Jul 03, 2022 12:01 pm
Figures (a) and (b) show two independent sequences of reads andwrites for data items in a distributed DB across various nodesP1.P2,P3,P4 on a timeline. "R: X=V" at Pi means read operation ondata item X returns value V at node Pi and "W: Y=V" at Pj meansdata item Y is written with value V by node Pj. In each case,evaluate if the sequence satisfies or violates casual consistency?Give reasons for the answers.
P1 P2 P3 P4 W: X=1 W: Y=6 R: X=2 R: X=1 time (a) R: Y=6 P1 P2 P3 P4 W: X-1 W: X=6 R: Y=2 R: X=6 W: Y=4 R: X=6 time (b) R: Y=4 R: X=1
P1 P2 P3 P4 W: X=1 W: Y=6 R: X=2 R: X=1 time (a) R: Y=6 P1 P2 P3 P4 W: X-1 W: X=6 R: Y=2 R: X=6 W: Y=4 R: X=6 time (b) R: Y=4 R: X=1