Incrementally Updated Backups: A One Week Example


The basic example can be extended to provide fast recoverability to a window greater
than 24 hours. Alter the RECOVER COPY… WITH TAG to perform incomplete
recovery of the datafile copies to the point in time in the past where you want your
window of recoverability to begin. This example shows how to maintain a seven day
window:
RUN {
RECOVER COPY OF DATABASE WITH TAG ‘incr_update’
UNTIL TIME ‘SYSDATE – 7’;
BACKUP INCREMENTAL LEVEL 1 FOR RECOVER OF COPY WITH TAG ‘incr_update’
DATABASE;
}
The effect of the script is as follows:
■ On the first night the RECOVER COPY… UNTIL TIME statement has no effect,
and the BACKUP INCREMENTAL… FOR RECOVER OF COPY statement creates
the incremental level 0 copy.
■ On the second through seventh nights, the RECOVER COPY… UNTIL TIME
statement has no effect because TIME ‘SYSDATE – 7’ is still a time in the
future. The BACKUP INCREMENTAL… FOR RECOVER OF COPY statement
creates differetial incremental level 1 backups containing the block changes for the
previous day.
■ On the eighth and all subsequent nights night, the RECOVER COPY… UNTIL
TIME statement applies the level 1 incremental from seven days ago to the copy of
the database. The BACKUP INCREMENTAL… FOR RECOVER OF COPY
statement creates an incremental backup containing the changes for the previous
day.
As with the basic example, you have fast recoverability to any point in time between
the SCN of the datafile copies and the present, using block changes from the

incremental backups and individual changes from the redo logs. Because you have the
daily level 1 incrementals, you still never need to apply more than one day of redo.

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