Files - Expert Oracle Database Architecture - page 118

Connected to:
Oracle Database 12c Enterprise Edition Release 12.1.0.1.0 - 64bit Production
With the Partitioning, OLAP, Advanced Analytics and Real Application Testing options
SYS@ORA12CR1> grant sysdba to ops$tkyte;
Grant succeeded.
SYS@ORA12CR1> exit
Disconnected from Oracle Database 12c Enterprise Edition Release 12.1.0.1.0 - 64bit Production
With the Partitioning, OLAP, Advanced Analytics and Real Application Testing options
[tkyte@dellpe ~]$ sqlplus 'ops$tkyte/foobar'@ora12cr1 as sysdba
SQL*Plus: Release 12.1.0.1.0 Production on Tue Sep 3 14:23:25 2013
Copyright (c) 1982, 2013, Oracle. All rights reserved.
Connected to:
Oracle Database 12c Enterprise Edition Release 12.1.0.1.0 - 64bit Production
With the Partitioning, OLAP, Advanced Analytics and Real Application Testing options
SYS@ORA12CR1>
This created an entry in the password file for us, and Oracle will now keep the password in sync. If OPS$TKYTE
alters his password, the old one will cease working for remote SYSDBA connections and the new one will start working.
The same process is repeated for any user who was a SYSDBA but is not yet in the password file.
Change Tracking File
The change-tracking file is an optional file for use with Oracle 10 g Enterprise Edition and above. The sole purpose
of this file is to track what blocks have modified since the last incremental backup. With this, the Recovery Manager
(RMAN) tool can back up only the database blocks that have actually been modified without having to read the entire
database.
In releases prior to Oracle 10 g , an incremental backup would have had to read the entire set of database files
to find blocks that had been modified since the last incremental backup. So, if you had a 1TB database to which you
simply added 500MB of new data (e.g., a data warehouse load), the incremental backup would have read 1TB of data
to find that 500MB of new information to back up. So, the incremental backup would have stored significantly less
data in the backup, and it would have still read the entire database.
In Oracle 10 g Enterprise Edition and up, that's no longer the case. As Oracle is running, and as blocks are
modified, Oracle optionally maintains a file that tells RMAN what blocks have been changed. Creating this
change-tracking file is rather simple and is accomplished via the ALTER DATABASE command:
SYS@ORA12CR1> alter database enable block change tracking using file
2 '/home/ora12cr1/oradata/ORA12CR1/changed_blocks.bct';
Database altered.