Recover-ability, Backup, Recovery from Transactions failures,Log based recovery Check points

Recoverability is a fundamental concept in database management systems (DBMS) that ensures that the database can recover from any transaction failures, system failures, or other unexpected events. Backup and recovery are key components of a recoverability strategy.

Backup involves creating a copy of the database or its contents at a specific point in time. This copy is stored on a separate device or location to protect against hardware failures, human error, or other problems that might cause data loss. Backups can be full, incremental, or differential, depending on the amount of data being backed up and the frequency of backups.

Recovery involves restoring the database to a known state after a failure. The recovery process typically involves three steps: identifying the problem, restoring the database from a backup, and applying transaction logs to bring the database up to date.

Transaction logs are a critical part of the recovery process. They record all changes made to the database, including insertions, updates, and deletions. In the event of a failure, the transaction logs can be used to reconstruct the database to a consistent state.

Checkpointing is a technique used in DBMS to reduce the amount of work required for recovery. A checkpoint is a point in time when the system records the state of the database and transaction logs. This checkpoint serves as a reference point for recovery operations. By periodically checkpointing, the amount of work required to restore the database can be significantly reduced.

Log-based recovery is a common method used for recovery from transaction failures. In this approach, the DBMS uses the transaction logs to undo or redo transactions as necessary to bring the database back to a consistent state. This process involves identifying the transactions that were active at the time of the failure, undoing any changes made by those transactions, and then redoing the transactions to bring the database up to date.

In summary, recoverability is critical in a database management system to ensure that the database can recover from transaction failures, system failures, or other unexpected events. Backup and recovery are key components of a recoverability strategy. The recovery process involves restoring the database from a backup and applying transaction logs to bring the database up to date. Checkpoints and log-based recovery are techniques used to reduce the amount of work required for recovery.