DBMS · Question 14 · Hard
Consider the schedule S: r1(X), w2(X), w1(X), where ri and wi are read and write by transaction Ti. Which statement is true?
- S is conflict serializable and equivalent to T1 → T2
- S is conflict serializable and equivalent to T2 → T1
- S is not conflict serializable, because its precedence graph has a cycle
- S is not conflict serializable, but it is conflict equivalent to T2 → T1
Answer and explanation
Answer: C. S is not conflict serializable, because its precedence graph has a cycle
Explanation: r1(X) before w2(X) gives the edge T1 → T2, and w2(X) before w1(X) gives T2 → T1. The cycle means no serial order is conflict equivalent to S.
Previous: Relation R(A, B, C) has the single functional dependency B → C. It is… · Next: Relation R(A, B, C) has the functional dependencies AB → C and C → B. Which is…
Practise dbms
Try a fresh set of dbms questions with an explanation after every answer, free and without signing up: DBMS practice. Or sit a full placement mock test.
More dbms questions
- In a B+ tree index, where are the pointers to actual data records stored?
- Relation R(A, B, C, D) has exactly one candidate key, A. How many superkeys…
- Relation R(A, B, C) has the single functional dependency B → C. It is…
- Relation R(A, B, C) has the functional dependencies AB → C and C → B. Which is…
- A column in the Enrollment table that refers to the primary key of the Student…
- Which ACID property guarantees that once a transaction has committed, its…
- In a relational database, what is a view?
- In an ER diagram (Chen notation), how is a multivalued attribute such as a…
- Which data model stores data as tables (relations) made of rows and columns?
- Relation R(A, B, C, D, E) has the functional dependencies A → B, BC → D and D…
More technical & programming practice
SQL · Operating Systems · Computer Networks · Software Engineering · Cloud & DevOps · GenAI Basics · Pseudo-code · C Programming
LogicWiz Exams home · All practice topics · Placement mock tests · Daily 10 challenge