What is a transaction?

A transaction is a series of operations performed as a logical unit. A logical unit of work must have four attributes, calledAcid(Atomicity, consistency, isolation, and durability) attributes can be a transaction only in this way: atomicity, the transaction must be an atomic unit of work; modifications to its data must be either performed in all, or none of them are executed. Consistency: when the transaction is completed, all data must be consistent. In related databases, all rules must be applied to transaction modifications to maintain the integrity of all data. All internal data structures (suchBTree indexes or two-way linked lists) must be correct. Isolation. modifications made by a concurrent firm must be isolated from those made by any other concurrent firm. The status of the data when the transaction is viewing the data is either the status before the transaction is modified or the status after the transaction is modified. The transaction does not view the data in the intermediate status. This is called serializability because it can reload the starting data and replays a series of transactions so that the State at the end of the data is the same as that of the original transaction execution. Durability: after the transaction is completed, its impact on the system is permanent. This modification will be maintained even if a system failure occurs.