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Maintaining the Control File

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Objectives

After completing this lesson, you should be able to do

the following:

• Eplain the uses of the control file

• !ist the contents of the control file• Multiple and manage the control file

• Manage the control file with Oracle Managed Files

"OMF#

• Obtain control file information

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Control File

• A small binary file

• $efines current state of physical database

• Maintains integrity of database

• %e&uired: – At MOUNT state during database start up

 – 'o operate the database

• !in(ed to a single database

• !oss may re&uire recovery• )i*ed initially by

CREATE DATABASE

Controlfiles

$atabase

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Control File Contents

A control file contains the following entries:

• $atabase name and identifier 

• 'ime stamp of database creation

• 'ablespace names• +ames and locations of data files and online redo

log files

• Current online redo log file se&uence number 

• Chec(point information• egin and end of undo segments

• %edo log archive information

• ac(up information

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Multipleing the Control File

CONTROL_FILES=

$HOME/ORADATA/u01/ctrl01.ctl, $HOME/ORADATA/u02/ctrl02.ctl

$is( - "u.-# $is( / "u./#

 ctrl02.ctlctrl01.ctl

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Multipleing the Control File

0hen 1sing )2F3!E

-4 Alter the )2F3!E:

/4 )hut down the database:

54 Create additional control files:

64 )tart the database:

 ALTER SSTEM SET c!"tr!l_#l%& ='$HOME/ORADATA/u01/ctrl01.ctl','$HOME/ORADATA/u02/ctrl02.ctl' SCO(E=S(FILE)

c* $HOME/ORADATA/u01/ctrl01.ctl$HOME/ORADATA/u02/ctrl02.ctl

&t+rtu*

&ut-!" %-+t%

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Multipleing the Control File

0hen 1sing 2F3!E

-4 )hut down the database:

/4 Create additional control files:

54 Add control file names to 2F3!E:

64 )tart the database:

&ut-!" %-+t%

CONTROL_FILES = $HOME/ORADATA/u01/ctrl01.ctl,$HOME/ORADATA/u02/ctrl02.ctl

c* $HOME/ORADATA/u01/ctrl01.ctl$HOME/ORADATA/u02/ctrl02.ctl

&t+rtu*

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Managing Control Files with OMF

• OMF is created if the CONTROL_FILES parameter isnot specified4

• !ocations are defined by

DB_CREATE_ONLINE_LO_DEST_"4• +ames are uni&uely generated and displayed in the

+l%rtSID.l!4

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Obtaining Control File 3nformation

3nformation about control file status and locations can

be retrieved by &uerying the following views4

• 3$CONTROLFILE: !ists the name and status of all

control files associated with the instance• 3$(ARAMETER : !ists status and location of all

parameters

• 3$CONTROLFILE_RECORD_SECTION: 2rovidesinformation about the control file record sections

• SHO4 (ARAMETER CONTROL_FILES: !ists the name,status, and location of the control files

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)ummary

3n this lesson, you should have learned how to:

• Multiple the control file when using an )2F3!E

• Multiple the control file when using an "t.!r+

• Manage the control files using OMF

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2ractice 7 Overview

'his practice covers the following topics:

• )tarting the database without a control file

• Multipleing an eisting control file