Sunday, April 25, 2010

Basic transaction concepts

This is mostly referred as "ACID" properties.

So, what are they?

  • Atomicity - When Two or more transactions are taking place, either all of them are committed or none of them are committed.

  • Consistency - That is, after a transaction, valid and new data exists in the database or the data returned to its original state. ROLLBACK function provides the facility of returning data to its original state.
  • Isolation – During a transaction, data must be in an isolated level there by not allowing other transactions to access it.
  • Durability - Data is still available even if the server fails. This is achieved by CHECKPOINTS and DATABASE RECOVERY PROECESS.