Transaction Management

1. Transaction Management by Benjamin Nguyen

2. Overview Transaction Properties of transaction Pessimistic & optimistic techniques Locking No lock techniques Oracle recovery tools

3. Transaction An action, or series of actions, carried out by a single user or application program, which reads or updates the contents of the database

4. Properties of Transaction ACID Atomicity: �all or nothing� property. (Responsible by DBMS recovery subsystem) Consistency: database must be transform from one consistent state to another consistent state.

5. Properties of Transaction (cont.) ACID Isolation: transaction execute independently of one another. (Responsible by concurrency control) Durability: The effects of a successfully completed (committed) transaction are permanently recorded in the database and must not be lost because of a subsequent failure (Responsible by recovery subsystem)

6. Over view of Database

7. Pessimistic & Optimistic techniques Pessimistic Check for conflict when read/write Optimistic Only check for conflict when the transaction wishes to commit

8. Pessimistic & Optimistic techniques Pessimistic Using locking techniques Optimistic The concurrency control that does not use lock and it involve the following phases: Read phase Validation phase Write phase

9. Optimistic Techniques