Distributed Transaction Management, Autumn 2003 , Exercise 2
Due Tue 4.11.2003

1. Study message round trip time between two computers.

2. Based on an answer to the previous problem, how well should
computers be synchronised for synchronisation work as
accurately as logical time?

3. Implement vector timestamping. The number of participants
needs to be known before the timestamping starts. The number
may be fixed (but at least four). The processes only need
to exchange messages and print out what happens (including
timestamps).

4. Show that if e.VT < e'.VT, then e happens before e'.

5. In two-phase locking the locks are only released
at commit (or rollback) time. What is the effect of
two-phase locking in terms of phantom deadlocks for simple
collection of local waits-for graphs?