This article answers the following queries :
· What is the control file in oracle?
· What are the functions of control file in oracle ?
· What are the control file contents ?
· Can database function properly without control file?
· Can we edit control file ?
· Who can modify control file ?
· At what time control file will be created?
What is control file in Oracle and what are its functions ?
Control file is a small binary file which is necessary for the database to start and operate successfully.
What are the functions of control file ?
Each control file is associated with only one database. Oracle continuosly updates control file during database use so this file must be available for writing whenever the database is in the open state. Control file will be created at the same time of database creation.
Whenever a datafile or a redolog file is added to , dropped or renamed in the database, the control file is updated to reflect the physical structural change.
These changes are recorded in control file which facilitates :
- Oracle to identify the files that are required or available in case database recovery is needed
- Oracle to identify the datafiles and redolog files to open during database startup.
Can database function properly without control file?
No. Database cannot function properly if the control file is not available.
Can we edit control file ? Who can modify control file ?
Please note control file cannot be edited by database administrator or by any user. Control file information can only be modified by Oracle.
Contents of control files :
- Control file contains information such as
- Database name
- Timestamp of database creation
- Tablespace information
- The log history
- Archive log information
- Current log sequence number
- Checkpoint information
- Names and locations of associated datafiles and redolog files
- Datafile copy information
- Datafile offline ranges
- Backup set and backup related information
- Backup datafile and redolog information
Hi Durga Prasad,
ReplyDeleteit is great to have blog like this.....can you please post detail steps(starting to end) regarding DB refresh, errors pertaining to control file...
It will be quiet useful.....
Thanks a lot
Nice post. Thank you so much for explaining the usage and functioning of a control in Oracle. You have briefly explained all about it and I have understood it from this article.
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Hi. Good thought.. I have performed DB refresh on dual stack systems. After performing that java stack did not start. May I know solution for this .
ReplyDeleteHi Durga Prasad
ReplyDeleteIt is great to have a blog like this could you pls post the what is the difference between redo log and undo table space management
Its really great information..Thanks for sharing this informative blog..
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Very informative. Thank you!
ReplyDeleteHi Durga..:) really amazing and helpful...Thanku
ReplyDeletewhat is the location of control file?
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DeleteIt will provide you the locations .
It is amazing and wonderful to visit your site.Thanks for sharing this information,this is useful to me. oracle training in chennai
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