A reader submitted this via e-mail without explanation whether these questions were used for hiring a DBA at Oracle Corp., or whether it was the Oracle database admin position that someone interviewed for somewhere else. Update: The questions were written by James Koopman for DatabaseJournal back in 2003.
- Explain the difference between a hot backup and a cold backup and the benefits associated with each. - A hot backup is basically taking a backup of the database while it is still up and running and it must be in archive log mode. A cold backup is taking a backup of the database while it is shut down and does not require being in archive log mode. The benefit of taking a hot backup is that the database is still available for use while the backup is occurring and you can recover the database to any point in time. The benefit of taking a cold backup is that it is typically easier to administer the backup and recovery process. In addition, since you are taking cold backups the database does not require being in archive log mode and thus there will be a slight performance gain as the database is not cutting archive logs to disk.
- You have just had to restore from backup and do not have any control files. How would you go about bringing up this database? - I would create a text based backup control file, stipulating where on disk all the data files where and then issue the recover command with the using backup control file clause.