Database Management System: Unit III: Transactions

Schedules

Transactions - Database Management System

Schedule is an order of multiple transactions executing in concurrent environment.

Schedules

Schedule is an order of multiple transactions executing in concurrent environment. Following figure represents the types of schedules.

Serial schedule: The schedule in which the transactions execute one after the other is called serial schedule. It is consistent in nature. For example : Consider following two transactions T1 and T2

All the operations of transaction T1 on data items A and then B executes and then in transaction T2 all the operations on data items A and B execute. The R stands for Read operation and W stands for write operation.

Non serial schedule: The schedule in which operations present within the transaction are intermixed. This may lead to conflicts in the result or inconsistency in the resultant data. For example-

Consider following two transactions,

The above transaction is said to be non serial which result in inconsistency or conflicts in the data.

Database Management System: Unit III: Transactions : Tag: : Transactions - Database Management System - Schedules