Session Numbers

DP4 displays the session numbers of the database and transaction log when you back up or restore the database, indicating:

• How many backups have been taken of the database.
• How many backups have been taken of the transaction log.

The database session number is incremented after any type of backup, including transaction-only and dummy backups. The transaction log session number is only incremented when a log is backed up.

Labelling your backup disks with the session number information enables you to ensure that in the event of a non-recoverable database error:

• The correct database can be restored.

• The correct transaction log, or sequence of them, can be applied to the database.

To view the session numbers for the last backed up database and transaction log, use option 1 - Status display of the Database Integrity Checking utility.

To reset the database and transaction log session numbers to 1, use option 7 - Version/Security of the MAKEDB utility.

We recommend you run the database integrity check (DBCHECK) as part of the backup process for these reasons:

• Restoring a corrupt backup wastes a great amount of time.
• Restoring an older backup than necessary and its associated log files is time consuming and error prone.