1.3 Atomicity and Two-Phase Commit
Distributed systems make atomicity harder
Suppose a transaction updates data managed by two DB systems.
One DB system could commit the transaction, but a failure could prevent the other system from committing.
The solution is the two-phase commit protocol.
Abstract “DB system” by resource manager (could be a SQL DBMS, message mgr, queue mgr, OO DBMS, etc.)