Oracle: block change tracking¶
- Title:
Oracle: block change tracking
- Author:
Douglas O’Leary <dkoleary@olearycomputers.com>
- Description:
Oracle: block change tracking
- Date created:
07/27/2010
- Date updated:
07/27/2010
- Disclaimer:
Standard: Use the information that follows at your own risk. If you screw up a system, don’t blame it on me…
Block change tracking is used in conjunction with incremental backups. The block change tracking file, as you might imagine, is used to track the changes at the block level to each of the datafiles.
The block change tracking file size is automatically determined. It should be roughly 1/30,000 of the database size. The absolute minimum size is 320k per datafile so the file for my little database will be 5*320/1024 = 1.56 megs. The file will hold enough data to support 8 days of incremental backups. Your base backup, then, has to be done minimally, once a week.
To enable block change tracking:
alter database enable block change tracking using file '${absolute_path}' [ reuse ]
To disable block change tracking:
alter database disable block change tracking
To identify status of block change tracking:
SQL> select * from v$block_change_tracking; STATUS FILENAME BYTES ---------- --------------------------------------------- ---------- DISABLED or SQL> select * from v$block_change_tracking; STATUS FILENAME BYTES ---------- --------------------------------------------- ---------- ENABLED /oracle/block_change/oci1_bc.fil 11599872