Transactions, Serializability and Concurrency Control: GATE CS previous year questions (Databases)

GATE CS 2026 Set 2MCQ1 markEasy (estimate)
GATE CS 2026 Set 2, Q.20
Consider concurrent execution of two transactions $T_{1}$ and $T_{2}$ in a DBMS, both of which access a data object $A$ . For these two transactions to not conflict on $A$ , which one...
Transactions, Serializability and Concurrency Control
GATE CS 2025 Set 1MCQ1 markEasy (estimate)
GATE CS 2025 Set 1, Q.15
A schedule of three database transactions $T_{1}$ , $T_{2}$ , and $T_{3}$ is shown. $R_{i} (A)$ and $W_{i} (A)$ denote read and write of data item $A$ by transaction $T_{i}$ , $i = 1, 2, 3$ . The...
Transactions, Serializability and Concurrency Control
GATE CS 2025 Set 2MSQ1 markEasy (estimate)
GATE CS 2025 Set 2, Q.27
An audit of a banking transactions system has found that on an earlier occasion, two joint holders of account $A$ attempted simultaneous transfers of Rs. 10000 each from account...
Transactions, Serializability and Concurrency Control
GATE CS 2025 Set 2MSQ2 marksEasy (estimate)
GATE CS 2025 Set 2, Q.53
Consider the database transactions T1 and T2, and data items X and Y. Which of the schedule(s) is/are conflict serializable? Transaction T1 Transaction T2 R1(X) W2(X) W1(Y) W2(Y...
Transactions, Serializability and Concurrency Control
GATE CS 2024 Set 1MSQ2 marksEasy (estimate)
GATE CS 2024 Set 1, Q.46
Consider the following read-write schedule $S$ over three transactions $T_{1}, T_{2}$ , and $T_{3}$ , where the subscripts in the schedule indicate transaction IDs…
Transactions, Serializability and Concurrency Control
GATE CS 2024 Set 2MCQ1 markEasy (estimate)
GATE CS 2024 Set 2, Q.19
Once the DBMS informs the user that a transaction has been successfully completed, its effect should persist even if the system crashes before all its changes are reflected on d...
Transactions, Serializability and Concurrency Control
GATE CS 2024 Set 2MSQ1 markEasy (estimate)
GATE CS 2024 Set 2, Q.27
Which of the following statements about the Two Phase Locking (2PL) protocol is/are TRUE?
Transactions, Serializability and Concurrency Control
GATE CS 2022MCQ2 marksMedium (estimate)
GATE CS 2022, Q.39
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.…
Transactions, Serializability and Concurrency Control
GATE CS 2021 Set 1MSQ1 markMedium (estimate)
GATE CS 2021 Set 1, Q.23 (CS Q.13)
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 recover...
Transactions, Serializability and Concurrency Control
GATE CS 2021 Set 1MCQ2 marksEasy (estimate)
GATE CS 2021 Set 1, Q.42 (CS Q.32)
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.…
Transactions, Serializability and Concurrency Control
GATE CS 2021 Set 2MCQ2 marksMedium (estimate)
GATE CS 2021 Set 2, Q.42 (CS Q.32)
Let $S$ be the following schedule of operations of three transactions $T_{1}$ , $T_{2}$ and $T_{3}$ in a relational database system…
Transactions, Serializability and Concurrency Control
GATE CS 2020MCQ2 marksMedium (estimate)
GATE CS 2020, Q.47 (CS Q.37)
Consider a schedule of transactions $T_{1}$ and $T_{2}$ given below.…
Transactions, Serializability and Concurrency Control
GATE CS 2019MCQ1 markMedium (estimate)
GATE CS 2019, Q.21 (CS Q.11)
Consider the following two statements about database transaction schedules: I. Strict two-phase locking protocol generates conflict serializable schedules that are also recovera...
Transactions, Serializability and Concurrency Control
GATE CS 2017 Set 1MCQ2 marksMedium (estimate)
GATE CS 2017 Set 1, Q.42 (CS Q.42)
In a database system, unique timestamps are assigned to each transaction using Lamport's logical clock. Let $TS (T_{1})$ and $TS (T_{2})$ be the timestamps of transactio...
Transactions, Serializability and Concurrency Control
GATE CS 2017 Set 2NAT2 marksHard (estimate)
GATE CS 2017 Set 2, Q.44 (CS Q.44)
Two transactions $T_{1}$ and $T_{2}$ are given as $T_{1} T_{2} : r_{1} (X) w_{1} (X) r_{1} (Y) w_{1} (Y) : r_{2} (Y) w_{2} (Y) r_{2} (Z) w_{2} (Z)$ where $r_{i} (V)$ denotes a...
Transactions, Serializability and Concurrency Control
GATE CS 2016 Set 1MCQ1 markEasy (estimate)
GATE CS 2016 Set 1, Q.32 (CS Q.22)
Which one of the following is NOT a part of the ACID properties of database transactions?
Transactions, Serializability and Concurrency Control
GATE CS 2016 Set 1MCQ2 marksEasy (estimate)
GATE CS 2016 Set 1, Q.61 (CS Q.51)
Consider the following two phase locking protocol. Suppose a transaction $T$ accesses (for read or write operations), a certain set of objects ${O_{1}, \dots, O_{k}}$ . This is don...
Transactions, Serializability and Concurrency Control
GATE CS 2016 Set 2MCQ1 markEasy (estimate)
GATE CS 2016 Set 2, Q.32 (CS Q.22)
Suppose a database schedule $S$ involves transactions $T_{1}, \dots, T_{n}$ . Construct the precedence graph of $S$ with vertices representing the transactions and edges representing...
Transactions, Serializability and Concurrency Control
GATE CS 2016 Set 2MCQ2 marksMedium (estimate)
GATE CS 2016 Set 2, Q.61 (CS Q.51)
Consider the following database schedule with two transactions, $T_{1}$ and $T_{2}$ . $S = r_{2} (X); r_{1} (X); r_{2} (Y); w_{1} (X); r_{1} (Y); w_{2} (X); a_{1}; a_{2}$ where $r_{i} (Z)$ denotes a read o...
Transactions, Serializability and Concurrency Control
GATE CS 2015 Set 2MCQ1 markEasy (estimate)
GATE CS 2015 Set 2, Q.11 (CS Q.1)
Consider the following transaction involving two bank accounts $x$ and $y$ .…
Transactions, Serializability and Concurrency Control
GATE CS 2015 Set 2MCQ2 marksMedium (estimate)
GATE CS 2015 Set 2, Q.56 (CS Q.46)
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);…
Transactions, Serializability and Concurrency Control
GATE CS 2015 Set 3MCQ2 marksMedium (estimate)
GATE CS 2015 Set 3, Q.39 (CS Q.29)
Consider the following partial Schedule $S$ involving two transactions $T 1$ and $T 2$ . Only the read and the write operations have been shown. The read operation on data item $P$ ...
Transactions, Serializability and Concurrency Control
GATE CS 2014 Set 1MCQ2 marksMedium (estimate)
GATE CS 2014 Set 1, Q.39 (CS Q.29)
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...
Transactions, Serializability and Concurrency Control
GATE CS 2014 Set 2MCQ2 marksMedium (estimate)
GATE CS 2014 Set 2, Q.39 (CS Q.29)
Consider the following schedule S of transactions T1, T2, T3, T4: | T1 | T2 | T3 | T4 | | :--- | :--- | :--- | :--- | | | Reads(X) | | | | | | Writes(X) / Commit | | | Write...
Transactions, Serializability and Concurrency Control
GATE CS 2014 Set 3MCQ2 marksMedium (estimate)
GATE CS 2014 Set 3, Q.39 (CS Q.29)
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)...
Transactions, Serializability and Concurrency Control
GATE CS 2012MCQ2 marksMedium (estimate)
GATE CS 2012, Q.27 (CS Q.27)
Consider the following transactions with data items $P$ and $Q$ initialized to zero: $T_{1}$ : read ( $P$ ); read ( $Q$ ); if $P = 0$ then $Q := Q + 1$ ; write ( $Q$ ). $T_{2}$ : read ( $Q$ );...
Transactions, Serializability and Concurrency Control

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