Jawaharlal Nehru Technological University Hyderabad
Jawaharlal Nehru Technological University Hyderabad MCA 2018 DISTRIBUTED DATABASES Previous Question Paper (January - 2018 - R15)
Note: This question paper contains two parts A and B. Part A is compulsory which carries 25 marks. Answer all questions in Part A. Part B consists of 5 Units. Answer any one full question from each unit. Each question carries 10 marks and may have a, b, c as sub questions.
PART - A
Answer all questions. Each question carries 5 marks.
What is replication transparency? What is its significance?
Answer
Replication transparency is the property in a distributed database system where the user or application is unaware that data is replicated across multiple nodes. The system automatically manages the existence of multiple copies of data, ensuring that all read and write operations appear as if they are performed on a single logical data object.
Its significance lies in improving availability and performance. By keeping copies closer to the user, latency is reduced, and if one node fails, the system can continue to operate using an alternative replica, thereby increasing fault tolerance.
Demonstrate the use of parametric queries.
Answer
Parametric queries are pre-compiled SQL statements that use placeholders for input values, allowing the same query structure to be executed repeatedly with different parameters. This improves security by preventing SQL injection and enhances performance through query plan reuse.
Example: Consider a query to retrieve employee details by ID:
In this case, the application passes a specific value (e.g., 101) to the placeholder at runtime. The database engine optimizes the query plan once, and subsequent calls with different IDs (e.g., 102, 103) use the cached execution plan, reducing overhead.
What is a nested transaction? Quote examples.
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Define reliability. How to measure reliability of a system?
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Give object query processor architectures.
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PART - B
With necessary reference structure explain various levels of distribution transparency. Quote an example application.
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What is an integrity constraint? What is its importance in distributed databases? Explain with suitable examples.
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How can qualified relations optimize query processing in distributed databases? Give illustrative examples.
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Describe a frame work for query optimization and explain general queries optimization.
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Explain the architectural aspects of distributed transactions.
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Give any one protocol for optimistic methods for concurrency control.
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What is a deadlock in distributed databases? Suggest various ways of handling them with illustrations.
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Explain two-phase commit protocol and compare it with three-phase commit protocols.
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What are the various approaches to detect inconsistencies in distributed databases data? Explain any one resolution method.
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Does common object request broker architecture provide interoperability? Justify your answer with necessary discussions.
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Explain transaction management in multi database system. Discuss challenges faced here compared to centralized database.
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