Saturday, 2 April 2016

Advantages of Concurrent Execution of Transactions in Database

Advantages of Concurrent Execution of Transaction in Database, Advantages of concurrent execution in DBMS, Benefits of concurrent execution


Advantages of Concurrent Execution of Transactions


Executing multiple transactions simultaneously is called concurrent executions. This has to be done with extra care because of the complications that would arise in some cases. Though executing transactions serially may involve consistency, safety and like features, we cannot compromise time on serial execution. We need to implement the concept of concurrent execution of transactions much more in a multi-user systems. This gives the following advantages;

  • Improved throughput 
    • Number of transactions that can be executed in a given amount of time is called as throughput. When we execute multiple transactions simultaneously that increases the transaction throughput.
  • Resource utilization 
    • It is about using various system resources like disks and CPUs concurrently. We all know that most of the times these resources are not utilized properly. When a transaction is using CPU we may permit other transaction to use disk I/O to fetch the data from disks to main memory. This way the utilization of resources can be increased.
  • Reduced waiting time 
    • Concurrent execution of transactions would reduce the waiting time of other transactions. Consider a situation where all transactions are executed serially. Transactions may be of any size. When executing serially, one long transaction is executing and a very small transaction may be on the queue for its turn. This increases the waiting time of small transaction. Hence, if we execute transactions simultaneously, the waiting time would be much reduced when compared to the serial execution.
  • Average response time of transaction increased 
    • The average time consumed by a transaction to complete since its start is called as the average response time. In concurrent execution, as multiple transactions are executing simultaneously by sharing the system resources, the waiting time is reduced which in turn increases the average response time.

But, concurrent execution of transactions has to happen safely. There are variety of concurrency control schemes to do this without violating ACID properties.

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