4.6 Data Transaction

The process of ensuring that data is consistent

Computer to computer exchange of documents

Purchase Orders, invoices and shipping documents§

A single operation executed on data

A set of properties to ensure that the integrity of the database is maintained under all circumstances

Ensures transactions must be processed or cannot happen at all

A transaction must maintain the referential integrity rules between linked tables

Simultaneous executions of transactions should lead to the same results as if they were executed one after the other

Once a transaction has been executed it will remain so regardless of circumstances surrounding it, such as in the event of a power cut

The process of preventing simultaneous access to records in a database

To prevent inconsistencies or a loss of updates

Ensures that transactions do not overlap in time and therefore cannot interfere with each other or lead to updates being lost

Every object in the database has a read timestamp, which is updated whenever an object is read or written

Ensures no transactions are lost if two clients simultaneously try to update a record