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Principles of Distributed Database Systems
Principles of Distributed Database Systems
Exercise: Fragment F1: 100 queries from site A, 10 from B, 0 from C. Updates: 5 from A, 20 from B, 0 from C. Cost of remote read=1, remote write=10. Local read=0, local write=0 (costs). Find allocation. Local read=0, local write=0 (costs)
This article provides detailed exercise solutions and explanatory insights for the most common problem sets found in standard textbooks (e.g., Özsu & Valduriez’s Principles of Distributed Database Systems). Whether you are preparing for an exam or designing a resilient data architecture, these step-by-step solutions will solidify your understanding.
Site Autonomy: Can a single site function if the others go offline? Whether you are preparing for an exam or
Answer (in brief):
Smallest relation is F2 (500). Join F2 with F1 → size=50010000.01=5000. Then join with F3 → total cost: move F2 to F1(500) + move 5000 to F3(5000) =5500.
Better: Join F2 with F3 first: 50020000.01=10,000; then with F1: cost 500 +10,000=10,500.
Best: Move smallest (F2) to any site first, then join with the next smallest intermediate.
Solution
Question: Is there a global deadlock? How to detect?
Scenario:
Coordinator C, Participants P1, P2. All vote YES. Coordinator sends COMMIT, fails after writing COMMIT log but before sending to P2. P1 receives COMMIT, P2 still in READY state. P1 receives COMMIT