Concurrent Executions Multiple transactions are allowed to run concurrently in the system. Advantages are: increased processor and disk utilization,leading to better transaction throughput:one transaction can be using the CPU while another is reading from or writing to the disk reduced average response time for transactions:short transactions need not wait behind long ones. Concurrency control schemes-mechanisms to achieve isolation;that is,to control the interaction among the concurrent transactions in order to prevent them from destroying the consistency of the database Will study in Chapter 16,after studying notion of correctness of concurrent executions. Database System Concepts-5th Edition,Sep 10,2005. 15.11 ©Silberschat乜，Korth and SudarshanDatabase System Concepts - 5 15.11 ©Silberschatz, Korth and Sudarshan th Edition, Sep 10, 2005. Concurrent Executions Multiple transactions are allowed to run concurrently in the system. Advantages are: increased processor and disk utilization, leading to better transaction throughput: one transaction can be using the CPU while another is reading from or writing to the disk reduced average response time for transactions: short transactions need not wait behind long ones. Concurrency control schemes – mechanisms to achieve isolation; that is, to control the interaction among the concurrent transactions in order to prevent them from destroying the consistency of the database Will study in Chapter 16, after studying notion of correctness of concurrent executions