Database PowerPoint Presentation Lectures by Dr Patrick Ozoh Dept of ICT Osun State University
A transaction is a sequence of DML commands that forms a logical unit of work Example: transferring money from one bank account to another Transaction Management A transaction is a sequence of DML commands that forms a logical unit of work Example: transferring money from one bank account to another Some Definitions Atomicity - a transaction must execute completely or not at all Consistency - once a transaction completes successfully, the database must be in a consistent state Isolation: A transaction must not be affected by other transactions that are executing concurrently Durability: Once a transaction compketes successfully, its effect must persist even in the presence of system failures Concurrency control Concurrency control is a database management systems (DBMS) concept meant to coordinate simultaneous transactions while preserving data integrity. Control protocols ensures atomicity, isolation, and serializability of concurrent transactions Concurrency control protoc