Two advantages exist to archiving redo log Recovery A database backup together

Two advantages exist to archiving redo log recovery a

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Two advantages exist to archiving redo log: Recovery: A database backup, together with online and archived redo log files can guarantee recovery of all committed transaction. Backup: Can be performed while the database is open. By default a database is created in NOARCHIVELOG mode
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Archived Redo Log Files Archiving redo log files is accomplished by ARCn(Aechiver) or manually through SQL statement. An entry in the control file recording the archive log name, log sequence number, and high and low SCN number is made whenever a redo log is successfully archived. A filled redo log file cannot be reused until a checkpoint has taken place and redo log file has been backed up the ARCn process. Archived redo log files can be multiplexed. Archived redo log files must be maintained by the DBA.
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Overview
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Database Storage Hierarchy
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SYSTEM and Non-SYSTEM Tablespaces SYSTEM tablespace: Created with the database Contains the data dictionary Contains the SYSTEM undo segment Non-SYSTEM tablespaces: Separate segments Ease space administration Control amount of space allocated to a user
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