Saturday, April 30, 2011

Control File Contents

A control file contains information about the associated database that is required for access by an instance, both at startup and during normal operation. Control file information can be modified only by Oracle Database; no database administrator or user can edit a control file. It contains (but is not limited to) the following types of information :
  • Database information (RESETLOGS SCN and their time stamp)
  • Archive log history
  • Tablespace and datafile records (filenames, datafile checkpoints, read/write status, offline or not).
  • Redo threads (current online redo log)
  • Database's creation date
  • database name
  • current archive log mode
  • Log records (sequence numbers, SCN range in each log)
  • RMAN catalog
  • Database block corruption information
  • Database ID, which is unique to each DB.                                                                                                                                                                                                                                                                                              
The location of the control files is specified through the control_files init parameter file .

Size of control files :
The size of the control files is governed by the following parameters
  • maxlogfiles
  • maxlogmembers
  • maxloghistory
  • maxinstances
  • control_file_record_keep_time
Sections :
The controlfile contains the following sections:
Archives Log (reusable)
Backup Corruption (reusable)
Backup Datafile (reusable)
Backup Piece (reusable)
Backup Redolog (reusable)
Backuo Set (reusable)
Backup spfile
CKPT Process
Copy Corruption (reusable)
Datafile Copy (reusable)
Datafile History
Database Incarnation
Deleted Objects (reusable)
Flashback Log
Instance Space Reservation
Log History (reusable)
Offline Range (reusable)
Recovery Destination
Removable Recovery Files
Rman Status
Rman Configuration
Redo Threads
Redo Logs
Temporary Filename
Thread Instance Name Mapping
Proxy Copy

The  minimum  number of  days that  a  reusable  record  is kept  in  the  controlfile is controlled  by  the control_file_record_keep_time parameter. These sections consist of records. The size, total number  and number of used record are exposed through v$controlfile_record_section.

To Check the information inside controlfile  use the below command  :
SQL> alter database backup controlfile to trace as   'C:\CREATE_CONTROL.sql' ;

Enjoy      :-)


Anonymous said...

what is the difference between reuseable and non reuseable sections ????

Anonymous said...

Difference between reuseable and non reusable section of control file