Compléter Session 05 - MISVersion en ligne Subject: Management Information Systems: Analysis, Design & Practice Lecturer: Professor Dr. Robert Regan Graduate School of Information Technology Siam University, Bangkok, Thailand par Prince Parham 1 deadlock valid operations Consistency execution orthogonally Durability 1 . In computer science , ACID ( Atomicity , , Isolation , ) is a set of properties that guarantee that database transactions are processed reliably . In the context of databases , a single logical operation on the data is called a transaction . For example , a transfer of funds from one bank account to another , even involving multiple changes such as debiting one account and crediting another , is a single transaction . 2 . In database systems , atomicity ( or atomicness ; from Greek a - tomos , undividable ) is one of the ACID transaction properties . In an atomic transaction , a series of database either all occur , or nothing occurs . 3 . Atomicity does not behave completely with regard to the other ACID properties of the transactions . For example , isolation relies on atomicity to roll back changes in the event of isolation failures such as ; consistency also relies on rollback in the event of a consistency - violation by an illegal transaction . Finally , atomicity itself relies on durability to ensure the atomicity of transactions even in the face of external failures . 4 . The consistency property ensures that any transaction will bring the database from one state to another . Any data written to the database must be valid according to all defined rules , including but not limited to constraints , cascades , triggers , and any combination thereof . 5 . The isolation property ensures that the concurrent of transactions results in a system state that could have been obtained if transactions are executed serially , i . e . one after the other . Each transaction has to execute in total isolation i . e . if T1 and T2 are being executed concurrently then both of them should remain unaware of each other's presence .
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