Principles Of Distributed Database Systems Exercise Solutions Extra Quality

Upon restart, coordinator sends COMMIT to P3 (if decision logged). If no decision logged and some participant already committed (via unilateral decision), P3 must commit → but this violates 2PC’s blocking property? Actually, 2PC can block if coordinator crashes without decision. That’s why 3PC is non-blocking. Exercise 4.2: Logging – Write-Ahead Log (WAL) in Distributed System Problem: Transaction T updates items A (site1) and B (site2). Show the steps for atomic commitment using WAL and 2PC.

Transmit 500 CustIDs (approx. 500*4 bytes = small). Upon restart, coordinator sends COMMIT to P3 (if

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. That’s why 3PC is non-blocking

Each site manages its own locks. T1 locks A at site1. T2 locks B at site2. T1 sends lock request for B to site2 → waits. T2 sends lock request for A to site1 → waits. Deadlock is distributed. Needs timeout or probe-based detection (e.g., wait-for graph across sites). Transmit 500 CustIDs (approx

Distributed 2PL avoids a central bottleneck but requires distributed deadlock detection (e.g., edge chasing algorithm). Exercise 3.2: Timestamp Ordering – Write Rule Conflict Problem: Given TS(T1)=10, TS(T2)=20. At site X, data item D has write_TS=5 , read_TS=5 . T2 issues write(D) . T1 issues write(D) later. Apply basic timestamp ordering (TO) rules.