Principles Of Distributed Database Systems Exercise Solutions ((hot)) Access

F1 = σ_Dept=‘Sales’(EMPLOYEE) F2 = σ_Dept=‘Eng’(EMPLOYEE) F3 = σ_Dept≠‘Sales’ ∧ Dept≠‘Eng’(EMPLOYEE)

write_TS(D)=5, read_TS(D)=5. TS(T2)=20 > both → allow. Update write_TS(D)=20.

Distributed 2PL avoids a central bottleneck but requires distributed deadlock detection (e.g., edge chasing algorithm).

A semi-join reduces the size of a relation before transferring it across the network.

Transaction T updates items A (site1) and B (site2). Show the steps for atomic commitment using WAL and 2PC. Distributed 2PL avoids a central bottleneck but requires

: Calculating the cost of moving data versus local processing for global queries.

We construct the Local Wait-For Graphs (LWFG) and combine them into a Global Wait-For Graph (GWFG).

Horizontal: A relation instance is completely decomposed if each tuple belongs to at least one fragment. Assuming 'New York', 'London', and 'Tokyo' are the only valid locations, every tuple maps to a fragment.

Cost2=2,000×40 bytes=80,000 bytesCost sub 2 equals 2 comma 000 cross 40 bytes equals 80 comma 000 bytes Show the steps for atomic commitment using WAL and 2PC

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Always verify that custom horizontal or vertical fragments satisfy completeness (no data lost), reconstruction (join or union restores the original table), and disjointness (no duplicate records across fragments).

If all surviving peers are in the READY state and no one knows the coordinator's intent, the protocol until the coordinator recovers to prevent split-brain anomalies. Summary of Core Performance Formulations

Coordinator P1 / P2 P3 (Crashes) | | | |--- PREPARE -------------->| | |--- PREPARE ------------------------------------------>| (Fails to vote) |<-- VOTE_COMMIT -----------| X | | X (Timeout! Aborts) | | | |--- GLOBAL_ABORT --------->| |<-- ACK -------------------| Solution & Operational Blueprint 1. Logging and State Machine Tracking TITLE) and PROJ(PNO

Horizontal partitioning divides a relation into tuples based on specific predicates.

Calculate and compare the total network transmission cost (in bytes) for a direct join versus a semi-join program. Strategy A: Direct Join (Ship R to Site 2)

Consider a global relation EMP(ENO, ENAME, TITLE) and PROJ(PNO, PNAME, BUDGET) . There is a relationship relation ASG(ENO, PNO, RESPONSIBILITY, DUR) .