States of Transaction

A transaction, from its inception to its completion or failure, passes through a series of states. Understanding this lifecycle is key to understanding how a DBMS manages operations. The first state is Active. This is the initial state where the transaction begins execution. The transaction remains in this state as long as it is executing its read and write operations. During this time, all changes are typically made to a temporary buffer in main memory. The next potential state is Partially Committed. After the final statement of the transaction has been executed, it enters the partially committed state. At this point, all operations are complete, but the changes have not yet been permanently written to the database. The system must now check that the transaction will not cause any consistency issues. If the check is successful, the transaction moves to the Committed state. This means it has completed successfully, and the changes are made permanent (durable) by writing them to the database's non-volatile storage. If the check in the partially committed state fails, or if the transaction encounters an error or is explicitly rolled back during the active state, it enters the Failed state. Once in the failed state, the transaction must be rolled back. This leads to the Aborted state. An aborted transaction is one where all its changes have been undone, and the database has been restored to its state prior to the transaction's start. Once a transaction is either committed or aborted, it is considered Terminated.