tailieunhanh - Maintaining the Control File

Control File The control file is a small binary file necessary for the database to start and operate successfully. Each control file is associated with only one Oracle database. Before a database is opened, the control file is read to determine whether the database is in a valid state to use. A control file is updated continuously by the Oracle server during database use, so it must be available for writing whenever the database is open. The information in the control file can be modified only by the Oracle server; no database administrator or end user can edit the control file | Maintaining the Control File Objectives After completing this lesson, you should be able to do the following: Explain the uses of the control file List the contents of the control file Multiplex and manage the control file Manage the control file with Oracle Managed Files (OMF) Obtain control file information Control File A small binary file Defines current state of physical database Maintains integrity of database Required: At MOUNT state during database start up To operate the database Linked to a single database Loss may require recovery Sized initially by CREATE DATABASE Control files Database Control File The control file is a small binary file necessary for the database to start and operate successfully. Each control file is associated with only one Oracle database. Before a database is opened, the control file is read to determine whether the database is in a valid state to use. A control file is updated continuously by the Oracle server during database use, so it must be . | Maintaining the Control File Objectives After completing this lesson, you should be able to do the following: Explain the uses of the control file List the contents of the control file Multiplex and manage the control file Manage the control file with Oracle Managed Files (OMF) Obtain control file information Control File A small binary file Defines current state of physical database Maintains integrity of database Required: At MOUNT state during database start up To operate the database Linked to a single database Loss may require recovery Sized initially by CREATE DATABASE Control files Database Control File The control file is a small binary file necessary for the database to start and operate successfully. Each control file is associated with only one Oracle database. Before a database is opened, the control file is read to determine whether the database is in a valid state to use. A control file is updated continuously by the Oracle server during database use, so it must be available for writing whenever the database is open. The information in the control file can be modified only by the Oracle server; no database administrator or end user can edit the control file. If for some reason the control file is not accessible, the database does not function properly. If all copies of a database’s control files are lost, the database must be recovered before it can be opened. Control File (continued) Sizing the Control File Keywords specified during the creation of the database affect the size of the control file. This is particularly significant when the parameters have large values. The size of the control file is influenced by the following keywords in the CREATE DATABASE or CREATE CONTROLFILE commands: MAXLOGFILES MAXLOGMEMBERS MAXLOGHISTORY MAXDATAFILES MAXINSTANCES Control File Contents A control file contains the following entries: Database name and identifier Time stamp of database creation Tablespace names Names and locations of data files and online redo .