Database Reference
In-Depth Information
2.
Create a table that has a character field:
SQL> create table cc(cc varchar2(20)) tablespace users;
3.
Insert a string into that table:
SQL> insert into cc values('DBWR does write');
4.
Force a checkpoint (which ensures that all modified buffers are written to disk):
SQL> alter system checkpoint;
From the OS, use the
strings
and
grep
commands to search for the string in the data file:
5.
$ strings /u01/dbfile/O12C/users01.dbf | grep "DBWR does write"
6.
Here is the output, proving that the database writer did write the data to disk:
DBWR does write
7.
Don't forget to take the tablespace out of backup mode:
SQL> alter tablespace users end backup;
Performing a Complete Recovery of an Archivelog
Mode Database
The term
complete recovery
means that you can recover all transactions that were committed before a failure
occurred.
Complete recovery
doesn't mean you that completely restore and recover the entire database. For instance,
if only one data file has experienced media failure, you need to restore and recover only the damaged data file to
perform a complete recovery.
■
If you have access to a test or development database, take the time to walk through every step in each of the
examples that follow. going through these steps can teach you more about backup and recovery than any documentation.
Tip
The steps outlined here apply to any database backed up while in archivelog mode. It doesn't matter if you made
a cold backup or hot backup. The steps to restore and recover data files are the same, as long as the database was in
archivelog mode during the backup. For a complete recovery, you need
•
to be able to restore the data files that have experienced media failure
•
access to all archive redo logs generated since the last backup was started
•
intact online redo logs
