Database Management System

In ACID properties, which component ensures that once a transaction is committed, it remains so?
(i) Atomicity
(ii) Durability
(iii) Isolation
(iv) Consistency

Consider the following action :
TRANSACTION.....
Commit;
ROLLBACK;

What does rollback do?
(i) Undoes the transactions before commit
(ii) Clears all transactions
(iii) Redoes the transactions before commit
(iv) No action

Which of the following is used to get back all the transactions back after rollback?
(i) Commit
(ii) Rollback
(iii) Flashback
(iv) Redo

Which of the following ensures no data is lost after a system crash?
(i) Commit log
(ii) View
(iii) Recovery manager
(iv) Trigger

Consider the schedule: R1(X), R2(X), W1(X), W2(X). The schedule is:

(i) View serializable only
(ii) Conflict serializable
(iii) Not serializable
(iv) Recoverable

Which of the following is a concurrency control protocol.
(i) Strict 2-phase locking protocol
(ii) Timestamp based protocol
(iii) Graph based protocol
(iv) All of the above

Under strict two-phase locking:

(i) Exclusive locks are held until commit/abort
(ii) Deadlocks are impossible
(iii) Locks can be released anytime
(iv) Transactions become serial

Briefly explain the ACID properties of the transactions to ensure integrity of the data.

Consider the transactions T1, T2 and T3 and 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).
Determine which of the above schedules are conflict – serializable.

Explain schedule and transaction. Define the concepts of recoverable, cascade less, and strict schedules, and compare them in terms of their recoverability.

Consider the three transactions T1, T2, and T3, and the schedules S1 and S2 given below. State whether each schedule is serializable or not. If a schedule is serializable, write down the equivalent serial schedule(s).
T1: r1 (X); r1 (Z); w1 (X);
T2: r2 (Z); r2 (Y); w2 (Z); w2 (Y);
T3: r3 (X); r3 (Y); w3 (Y);
S1: r1 (X); r2 (Z); r1 (Z); r3 (X); r3 (Y); w1 (X); w3 (Y); r2 (Y); w2 (Z); w2 (Y);
S2: r1 (X); r2 (Z); r3 (X); r1 (Z); r2 (Y); r3 (Y); w1 (X); w2 (Z); w3 (Y); w2 (Y);

List the ACID properties. Explain the usefulness of each.

What benefit is provided by rigorous two-phase locking? How does it compare with other forms of two-phase locking?

Define serializability. Explain conflict and view serializability.

Briefly explain the ACID property of database system.

Discuss 2 phase commit (2PC) protocol and time stamp-based protocol with suitable example. How the validation-based protocols differ from 2PC?

Explain two-phase locking protocol with an example.

Explain the immediate update and deferred update of recovery techniques.

Discuss the procedure of deadlock detection and recovery in transaction?

Explain concurrency control problems such as lost update, dirty read, and unrepeatable read.

Explain the concept of database recovery in detail. Discuss various recovery techniques such as log-based recovery, shadow paging, checkpointing, and recovery using deferred and immediate update strategies with suitable examples.

What do you mean by concurrent execution and serializability in database system?

What is two-phase locking protocol? Explain its working in detail. How can it guarantee serializability?

Discuss the various approaches for handling the deadlocks in dbms.

Write short notes on the following:
(b) Concurrency control

Write short notes on: Two-phase locking protocol

Write a short note on:

Database Recovery Techniques