2. Propose a distributed algorithm to efficiently refresh a snapshot at one site derived by pro-...

Transcribed Image Text:

2. Propose a distributed algorithm to efficiently refresh a snapshot at one site derived by pro- jection from a relation horizontally fragmented at two other sites. Give an example query on the view and base relations which produces an inconsistent result. 3. Consider the view EG that we discussed in class which uses relations EMP and ASG as base data and assume its state is also as shown in the course slides. Assume that tuple <E3, P3, Consultant, 10> from ASG is updated to <E3, P3, Engineer, 10>. (a) Apply the basic counting algorithm for refreshing the view EG. (b) What projected attributes should be added to view EG to make it self-maintainable? 2. Propose a distributed algorithm to efficiently refresh a snapshot at one site derived by pro- jection from a relation horizontally fragmented at two other sites. Give an example query on the view and base relations which produces an inconsistent result. 3. Consider the view EG that we discussed in class which uses relations EMP and ASG as base data and assume its state is also as shown in the course slides. Assume that tuple <E3, P3, Consultant, 10> from ASG is updated to <E3, P3, Engineer, 10>. (a) Apply the basic counting algorithm for refreshing the view EG. (b) What projected attributes should be added to view EG to make it self-maintainable?

Answer rating: 100% (QA)

2 To efficiently refresh a snapshot derived by projection from horizontally fragmented relations at two other sites you can use a distributed algorithm that involves coordination among the sites Each ... View the full answer