[計算機概論]課程參與

Object-oriented(物件導向) Database:
A database constructed by applying the object-oriented paradigm
– Each entity stored as a persistent object
– Relationships indicated by links between objects
– DBMS(資料庫管理系統) maintains inter-object links

Advantages of Object-oriented Databases
• Matches design paradigm of object-oriented applications
• Intelligence can be built into attribute handlers
• Can handle exotic data types
– Example: multimedia

Maintaining Database Integrity
• Transaction: A sequence of operations that must all happen together
– Example: transferring money between bank accounts
• Transaction log: A non-volatile record of each transaction’s activities, built before the transaction is allowed to execute
– Commit point: The point at which a transaction has been recorded in the log
– Roll-back: The process of undoing a transaction
• Simultaneous access problems
– Incorrect summary problem
– Lost update problem
• Locking = preventing others from accessing data being used by a transaction
– Shared lock: used when reading data
– Exclusive lock: used when altering data