Databases Test ...

There are three transactions T₁, T₂. and T₃ Transaction T₁ has 6 transactions, T₂ has 3 transactions and T₃ has 4 transactions. Find the number of non-serial schedule?

If wound and wait scheme is considered, which of the following will holds good?

If T22 requests a data item held by T23

If T24 requests a data item held by T23

where '22', '23' and '24' are time stamps in seconds

Which property of database transaction create an allusion than only 1 transaction is executed in system in spite of more than one transaction is executed in parallel manner?

Consider the following transactions with data items P and Q initialized to zero:

T1 : read(P)

read(Q)

if P = 0 then Q: = Q + 1;

write (Q);

T2: read (Q);

read (P);

if Q = 0 then P : = P + 1;

write (P);

Any non-seral interleaving of T1 and T2 for concurrent execution leads to

Which of the following statement is/are true?

I. A transaction writes a data item after it is read by an uncommitted transaction leads to an irrecoverable error in a database system.

II. Timestamp ordering protocol does not ensure freedom from deadlock

III. In case of disk crash, Among the ACID property, the durability property fails to make changes successfully in the database

Consider the following schedules:

Schedule 1:

T1	T2	T3
read(A)
read(B)
write(A)
	read(A)
	write(A)
		read(A)
abort

 

Schedule 2:

T1	T2	T3
read(A)
read(B)
write(A)
commit
	read(A)
	write(A)
	commit
		read(A)
		commit

 

Schedule 3:

T1	T2	T3
read(A)
read(B)
write(A)
commit
	read(A)
	write(A)
		read(A)
	abort
		commit

 

Which of the above schedules are cascadeless schedules?