Maintaining Redo logs and Control files

Maintaining Redo logs and Control files - Maintaining Redo...

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Maintaining Redo logs and Control files When an instance mounts, it reads the control file to locate data files and redo log files Provides most recent information of database, provides read consistency Contents: Database names, names and locations of data files and online redo log files, tablespace names, timestamp of database creation, current log sequence number, checkpoint information, log history, backup information V$CONTROLFILE, V$CONTROLFILE_RECORD_SECTION SELECT type, records_total FROM V$CONTROLFILE_RECORD_SECTION WHERE type=’DATAFILE’; SELECT * FROM v$controlfile; CONTROL_FILES initialization- , “---“) save C:\orant\database\initorcl.ora Each online redo log file in an online redo log group is an online redo log member Online redo log members- identical log sequence number, same size for each online redo log member Performance of an oracle database is affected by number and size of online log files and groups MAXLOGFILES- maximum number of online redo log groups MAXLOGMEMBERS LOG_FILES- decreases maximum number of groups of online redo log files for duration of current instance All changes made to database are stored sequentially in redo log bugger before online redo log groups are filled LGWR process begins: commit occurs, when redo log buffer is one-third full, before
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This note was uploaded on 02/25/2010 for the course MAT 443 taught by Professor Roberts during the Winter '10 term at University of Arizona- Tucson.

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Maintaining Redo logs and Control files - Maintaining Redo...

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