Restoring to an existing database

You can restore any database or table space backup image to an existing database. For a database-level restore, the backup image can differ from the existing database in its alias name, its database name, or its database seed. For a table-space level restore, you can restore a table space into an existing database only if the table space currently exists, and if it is the same table space; "same" means that the table space was not dropped and then recreated between the backup and the restore operation. The database on disk and in the backup image must be the same.

A database seed is a unique identifier for a database that does not change during the life of the database. The seed is assigned by the database manager when the database is created. DB2® always uses the seed from the backup image.

When restoring to an existing database, the restore utility:

• Deletes table, index, and long field data from the existing database, and replaces it with data from the backup image.
• Replaces table entries for each table space being restored.
• Retains the recovery history file, unless it is damaged or has no entries. If the recovery history file is damaged or contains no entries, the database manager copies the file from the backup image. If you want to replace the recovery history file you can issue the RESTORE command with the REPLACE HISTORY FILE option.
• Retains the authentication type for the existing database.
• Retains the database directories for the existing database. The directories define where the database resides, and how it is cataloged.
• Compares the database seeds. If the seeds are different:
  • Deletes the logs associated with the existing database.
  • Copies the database configuration file from the backup image.
  • Sets NEWLOGPATH to the value of the logpath database configuration parameter if NEWLOGPATH was specified on the RESTORE DATABASE command.
  If the database seeds are the same:
  • Deletes all log files if the image is for a non-recoverable database.
  • Deletes empty log files if the image is for a recoverable database. Non-empty log files are not affected.
  • Retains the current database configuration file.
  • Sets NEWLOGPATH to the value of the logpath database configuration parameter if NEWLOGPATH was specified on the RESTORE DATABASE command; otherwise, copies the current log path to the database configuration file. Validates the log path: If the path cannot be used by the database, changes the database configuration to use the default log path.