Checkpoints, Savepoints, and Transaction Rollback

Besides permitting concurrency, snapshot versioning transaction processing plays an important role in data recovery.

SAP Sybase IQ relies on transaction-related commands that help you recover a stable set of data in the event of system or media failure. The CHECKPOINT command sets a checkpoint, the SAVEPOINT command sets a savepoint, RELEASE SAVEPOINT releases savepoints, and ROLLBACK TRANSACTION rolls back transactions.

• Checkpoints
  A checkpoint marks a significant point in a transaction, when SAP Sybase IQ writes to disk certain information it tracks internally. SAP Sybase IQ uses this information during database recovery.
• Savepoints Within Transactions
  SAP Sybase IQ supports savepoints within a transaction.
• Transaction Rollback
  When you roll back a transaction, either automatically, or by explicit user request, you undo all of the operations in that transaction.
• System Recovery
  In the event of a system failure or power outage, or when you restart the database server after it has been stopped, SAP Sybase IQ attempts to recover automatically.
• How Transaction Information Aids Recovery
  The SAP Sybase IQ recovery mechanism is designed for a data warehouse enivronment, in which, typically, transactions are few but lengthy.
• Concurrency for Backups
  Backups may be performed concurrently with read and write operations.