Change transaction T₂ in Figure 20.2(b) to read

read_item(X);
X := X + M;
if X > 90 then exit
else write_item(X);

Discuss the final result of the different schedules in Figures 20.3(a) and (b), where M = 2 and N = 2, with respect to the following questions: Does adding the above condition change the final outcome? Does the outcome obey the implied consistency rule (that the capacity of X is 90)?

Figures 20.3(a) and (b):

Figure 20.2(b)

Transcribed Image Text:

(b) T2 read_item(X); X=X+ M; write_item(X);