Sybase IQ provides a full set of features that protect you from two types of computer failure, and from database inconsistency.
A system failure occurs when the computer or operating system goes down while there are partially completed transactions. This could occur when the computer is inappropriately turned off or rebooted, when another application causes the operating system to crash, or because of a power failure.
A media failure occurs when the database file, the file system, or the device storing the database file, becomes unusable.
After a system failure, Sybase IQ can usually recover automatically, so that you may not need to restore your database. Recovery from system failures is discussed in Chapter 13, “System Recovery and Database Repair.”
After media failure, or if for any reason the data in your database is inconsistent, you must restore your database. To protect your data in all of these situations, make regular backups of your databases. In particular, you should back up your database each time you finish inserting any large quantities of new data into the database.
When failures occur, the recovery mechanism treats transactions properly, as atomic units of work: any incomplete transaction is rolled back and any committed transaction is preserved. This ensures that even in the event of failure, the data in your database remains in a consistent state.
