Wednesday, October 6, 2010

Managing Backup & Recovery

What are the different methods of backing up oracle database ?
- Logical Backups
- Cold Backups
- Hot Backups (Archive log)

What is a logical backup ?
Logical backup involves reading a set of databse records and writing them into a file. Export utility is used for taking backup and Import utility is used to recover from backup.

What is cold backup ? What are the elements of it ?
Cold backup is taking backup of all physical files after normal shutdown of database. We need to take.
- All Data files.
- All Control files.
- All on-line redo log files.
- The init.ora file (Optional)

What are the different kind of export backups ?
Full back - Complete database
Incremental - Only affected tables from last incremental date/full backup date.
Cumulative backup - Only affected table from the last cumulative date/full backup date.

What is hot backup and how it can be taken ?
Taking backup of archive log files when database is open. For this the ARCHIVELOG mode should be enabled. The following files need to be backed up.
All data files. All Archive log, redo log files. All control files.

What is the use of FILE option in EXP command ?
To give the export file name.

What is the use of COMPRESS option in EXP command ?
Flag to indicate whether export should compress fragmented segments into single extents.

What is the use of GRANT option in EXP command ?
A flag to indicate whether grants on databse objects will be exported or not. Value is 'Y' or 'N'.

What is the use of INDEXES option in EXP command ?
A flag to indicate whether indexes on tables will be exported.

What is the use of ROWS option in EXP command ?
Flag to indicate whether table rows should be exported. If 'N' only DDL statements for the databse objects will be created.

What is the use of CONSTRAINTS option in EXP command ?
A flag to indicate whether constraints on table need to be exported.

What is the use of FULL option in EXP command ?
A flag to indicate whether full databse export should be performed.

What is the use of OWNER option in EXP command ?
List of table accounts should be exported.

What is the use of TABLES option in EXP command ?
List of tables should be exported.

What is the use of RECORD LENGTH option in EXP command ?
Record length in bytes.

What is the use of INCTYPE option in EXP command ?
Type export should be performed COMPLETE,CUMULATIVE,INCREMENTAL.

What is the use of RECORD option in EXP command ?
For Incremental exports, the flag indirects whether a record will be stores data dictionary tables recording the export.

What is the use of PARFILE option in EXP command ?
Name of the parameter file to be passed for export.

What is the use of PARFILE option in EXP command ?
Name of the parameter file to be passed for export.

What is the use of ANALYSE ( Ver 7) option in EXP command ?
A flag to indicate whether statistical information about the exported objects should be written to export dump file.

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