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Higher Study | DBMS | Transaction

Consider the following partial Schedule S involving two transactions T1 and T2. Only the read and the write operations have been shown. The read operation on data item P is denoted by read(P) and the write operation on data item P is denoted by write(P) Time Instance Transaction-id T1 T2 1 read(A)   2 write(A)   3   read(C) 4   write(C) 5   read(B) 6   write(B) 7   read(A) 8   Commit 9 read(B)     Schedule S   Suppose that the transaction T1 fails immediately after time instance 9. Which one of the following statements is correct?
To ensure integrity of the data, a database system should follow the ACID properties. What are these ACID properties?
Consider a Simple Checkpointing Protocol and the following set of operations in the log. (start, T4); (write, T4, y, 2, 3); (start, T1); (commit, T4); (write, T1, z, 5, 7); (Checkpoint); (start, T2); (write, T2, x, 1, 9); (commit, T2); start, T3); (write, T3, z, 7, 2); if a crash happens now and the system tries to recover using both undo and redo operations, what are the contents of the undo list and the redo list?
Consider a simple checkpointing protocol and the following set of operations in the log. (start, T4); (write, T4, y, 2, 3); (start, T1); (commit, T4); (write, T1, z, 5, 7); (checkpoint); (start, T2); (write, T2, x, 1, 9); (commit, T2); (start, T3), (write, T3, z, 7, 2); If a crash happens now and the system tries to recover using both undo and redo operations, what are the contents of the undo list and the redo list?
Suppose a database schedule 5 involves transactions T1, T2, .............Tn Consider the precedence graph of S with vertices representing the transactions and edges representing the conflicts. If S is serializable, which one of the following orderings of the vertices of the precedence graph is guaranteed to yield a serial schedule ?
Which of the following scenarios may lead to an irrecoverable error in a database system?
Let us assume that transaction T1 has arrived before transaction T2. Consider the schedule S=r1(A); r2(B) ; w2(A); w1(B) Which of the following is true?
Consider the transactions T1, T2, and T3 and the schedules S1 and S2 given below. T1: r1(X); r1(Z); w1(X); w1(Z) T2: r2(Y); r2(Z); w2(Z) T3: r3(Y); r3(X); w3(Y) S1: r1(X); r3(Y); r3(X); r2(Y); r2(Z); w3(Y); w2(Z); r1(Z); w1(X); w1(Z) S2: r1(X); r3(Y); r2(Y); r3(X); r1(Z); r2(Z); w3(Y); w1(X); w2(Z); w1(Z) Which one of the following statements about the schedules is TRUE?
Which one of the following makes permanently recorded transaction in the database?
Consider a schedule of transactions T1 and T2: T1 RA     RC   WD   WB Commit   T2   RB WB   RD   WC     Commit   Here, RX stands for “Read(X)” and WX stands for “Write(X)”. Which one of the following schedules is conflict equivalent to the above schedule?
Suppose a database schedule S involves transactions T1, …,Tn. Construct the precedence graph of S with vertices representing the transactions and edges representing the conflicts. If S is serializable, which one of the following orderings of the vertices of the precedence graph is guaranteed to yield a serial schedule? 
Which one of the following is NOT a part of the ACID properties of database transactions?
Consider the following four schedules due to three transactions (indicated by the subscript) using read and write on a data item x, denoted by r(x) and w(x) respectively. Which one of them is conflict serializable?
Consider the following log sequence of two transactions on a bank account, with initial balance 12000, that transfer 2000 to a mortgage payment and, then apply a 5% interest (i) T1 start (ii) T1 B old = 12000 new = 10000 (ii) T1 M old = 0 new = 2000 (iv) T1 commit (v) T2 start (vi) T2 B old = 10000 new = 10500 (vii) T2 commit Suppose the database system crashed just before log record 7 is written. When the system is restarted, which one statement is true of the recovery procedure?
Which of the following occurs when a transaction cannot proceed for an indefinite period of time while other transactions in the system continue normally?
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