In a concurrent transaction processing environment, ____________ problem may occur, which is while a transactions results were overwritten by the results from another transaction. To solve this problem, database systems use _________ approach. But this solution may cause another problem called as ________, which can be dealt with by approaches such as (A)_______________ or (B) _________________.

2. What is serializability and describe the way to achieve it.

3. Considering the following situation for the process of database recovery:

There are 3 transactions (T1, T2, T3) since the last backup (SAVE). T1 finished successfully before the latest checkpoint p1. T2 finished successfully after p1. T3 was aborted after p1 due to a main memory crash.

Describe/explain

(a). the database recovery processes regarding T1/T2/T3 if the memory crashes?

(b). the database recovery processes regarding T1/T2 /T3 if the hard drive crashes (in stead of memory crashes ) after p1 ?