Question 1 |

Let R_i(z) and W_i(z) denote read and write operations on a data element z by a transaction T_i, respectively. Consider the schedule S with four transactions.

S: R_4(x)R_2(x)R_3(x)R_1(y)W_1(y)W_2 (x)W_3 (y)R_4(y)

Which one of the following serial schedules is conflict equivalent to S?

S: R_4(x)R_2(x)R_3(x)R_1(y)W_1(y)W_2 (x)W_3 (y)R_4(y)

Which one of the following serial schedules is conflict equivalent to S?

T_1\rightarrow T_3\rightarrow T_4\rightarrow T_2 | |

T_1\rightarrow T_4\rightarrow T_3\rightarrow T_2 | |

T_4\rightarrow T_1\rightarrow T_3\rightarrow T_2 | |

T_3\rightarrow T_1\rightarrow T_4\rightarrow T_2 |

Question 1 Explanation:

Question 2 |

Let S be the following schedule of operations of three transactions T_1, T_2 \text{ and }T_3 in a relational database system:

R_2(Y), R_1(X), R_3(Z), R_1(Y)W_1(X), R_2(Z), W_2(Y), R_3(X), W_3(Z)

Consider the statements P and Q below:

P: S is conflict-serializable.

Q: If T_3 commits before T_1 finishes, then S is recoverable.

Which one of the following choices is correct?

R_2(Y), R_1(X), R_3(Z), R_1(Y)W_1(X), R_2(Z), W_2(Y), R_3(X), W_3(Z)

Consider the statements P and Q below:

P: S is conflict-serializable.

Q: If T_3 commits before T_1 finishes, then S is recoverable.

Which one of the following choices is correct?

Both P and Q are true | |

P is true and Q is false | |

P is false and Q is true | |

Both P and Q are false |

Question 2 Explanation:

Question 3 |

Let r_i(z) and w_i(z) denote read and write operations respectively on a data item z by a transaction T_i. Consider the following two schedules.

S1: r_1(x)r_1(y)r_2(x)r_2(y)w_2(y)w_1(x)

S2: r_1(x)r_2(x)r_2(y)w_2(y)r_1(y)w_1(x)

Which one of the following options is correct?

S1: r_1(x)r_1(y)r_2(x)r_2(y)w_2(y)w_1(x)

S2: r_1(x)r_2(x)r_2(y)w_2(y)r_1(y)w_1(x)

Which one of the following options is correct?

S1 is conflict serializable, and S2 is not conflict serializable | |

S1 is not conflict serializable, and S2 is conflict serializable | |

Both S1 and S2 are conflict serializable | |

Niether S1 nor S2 is conflict serializable |

Question 3 Explanation:

Question 4 |

Suppose a database system crashes again while recovering from a previous crash. Assume checkpointing is not done by the database either during the transactions or during recovery.

Which of the following statements is/are correct?

Which of the following statements is/are correct?

The same undo and redo list will be used while recovering again | |

The system cannot recover any further | |

All the transactions that are already undone and redone will not be recovered again | |

The database will become inconsistent |

Question 4 Explanation:

Question 5 |

Consider a schedule of transactions T1 and T2:

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?

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?

A | |

B | |

C | |

D |

Question 5 Explanation:

There are 5 questions to complete.

Question 34 of transaction misprinted

Thanks for your suggestion. We have corrected Question 34.

question 21, option b please correct

Thank You Suman Maity,

We have updated the option.

Please add DARK MODE😎. It will be very helpful.

Thank You Hrishikesh Roy,

We will consider this update.

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