MadeEasy Subject Test: Databases - Transactions

Question

Comments

i think 2 is the correct answer

plz correct me if i am wrong

Answer 1

s1: True: conflict serializable to schedule >> $T_{1}\rightarrow$$T_{2}\rightarrow T_{3}$

S2: True: allowed in basic  2PL.

s3: False

    strict recoverable schedule>> if transaction $T_{i}$ updates the data item A, then any other transaction $T_{j}$ not allowed to R(A) or W(A) until commit or rollback of $T_{i}$.

$T_{i}$	$T_{j}$
W(A)
.....
commit or rollback
	R(A) or W(A)

 

s4: False>>>  strict 2PL is basic 2PL in which all exclusive locks should be hold until commit or rollback

                    but here R$_{2}$(B) request for shared lock on B and B is already locked(xclusive) by   $T_{1}$.