1. Transaction management deals with the problems of always keeping the database in a consistent state even when concurrent accesses and failures occur. 2. A transaction consists of a sequence of read and write operations on the database, together with computation steps. 3. Durability is the property of transactions that requires each transaction to see a consistent database at all times. 4. Isolation refers to that property of transactions which ensures that once a transaction commits, its results are permanent and cannot be erased from the database. 5. The history of transaction execution at each site is called a global history. 6. Optimistic algorithms synchronize the concurrent execution of transactions early in their execution life cycle, whereas pessimistic algorithms delay the synchronization of transactions until their termination..

1. 1. Transaction management deals with the problems of always keeping the database in a
consistent state even when concurrent accesses and failures occur.
2. A transaction consists of a sequence of read and write operations on the database, together
with computation steps.
3. Durability is the property of transactions that requires each transaction to see a consistent
database at all times.
4. Isolation refers to that property of transactions which ensures that once a transaction commits,
its results are permanent and cannot be erased from the database.
5. The history of transaction execution at each site is called a global history.
6. Optimistic algorithms synchronize the concurrent execution of transactions early in their
execution life cycle, whereas pessimistic algorithms delay the synchronization of transactions until
their termination.