M.P. Johnson, DBMS, Stern/NYU, Sp2004
Concurrent execution is essential for performance.
Frequent, slow disk accesses
don’t waste CPU – keep running
Interleaving actions of different user programs
can lead to inconsistency:
e.g., two programs simultaneously withdraw from the same account
DBMS ensures such problems don’t arise:
users can pretend they are using a single-user system.