Difference between revisions of "Durability"
From Convivial Tools Database
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==Database durability== | ==Database durability== | ||
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The term "durability" is used with a rather different meaning with respect to database systems. According to the Wikipedia article on [http://en.wikipedia.org/wiki/Durability_%28computer_science%29 Durability (computer science)], database durability means that transactions that are committed will survive permanently and will not be undone by system failure. For example, if a flight booking database system reports that a seat has successfully been booked, then the seat will remain booked even if the system crashes: this is ensured by saving the transaction's log records to disk before acknowledging commitment. Durability also guarantees that the system will not rollback the transaction because the seat was double-booked: it must check availability before acknowledging that the seat has been booked. The only way a transaction can be undone after it has been committed is by a compensatory transaction. | The term "durability" is used with a rather different meaning with respect to database systems. According to the Wikipedia article on [http://en.wikipedia.org/wiki/Durability_%28computer_science%29 Durability (computer science)], database durability means that transactions that are committed will survive permanently and will not be undone by system failure. For example, if a flight booking database system reports that a seat has successfully been booked, then the seat will remain booked even if the system crashes: this is ensured by saving the transaction's log records to disk before acknowledging commitment. Durability also guarantees that the system will not rollback the transaction because the seat was double-booked: it must check availability before acknowledging that the seat has been booked. The only way a transaction can be undone after it has been committed is by a compensatory transaction. | ||
