Does the following transactions follow the 2PL (two Phase Locking) protocol? And explain your answer, if No rewrite the new Transactions after enforcing 2PL protocol?

T1 T2

read_lock (Y); read_lock (X);

read_item (Y); read_item (X);

unlock (Y); unlock (X);

write_lock (X); Write_lock (Y);

read_item (X); read_item (Y);

X:=X+Y; Y:=X+Y;

write_item (X); write_item (Y);

unlock (X); unlock (Y);

Q2 -

(a). What is meant by Roll-back and Roll-Forward?

(b). Discuss the analysis phase and REDO phase?