Questions about redo log files and archive files

Author: Msnch Time: 02-10-03 07:57

Questions about redo log files and archive files

What is the difference between redo log files and archive files? What content is included in them? Which of the following shall prevail if you want to restore the log files? Now I have read a book that is fuzzy.

Author: Snowhite2000 Time: 02-10-03 08:58

Log File: Online redo log file?
Archive file: Archived log files?

Log Files (redo log groups) are used cyclically. If you have three groups, the original file will be overwritten once. If one is full, loop to the next (WRAP), and copy the full file to archived log file ).

Author: Msnch Time: 02-10-03

If a problem occurs in the database, which of the following statements shall prevail?

Author: Snowhite2000 Time: 02-10-03 10: 00

The more you raise the question, the more you snowball.

What is the starting point of your question? Backup and recovery?
What is the role of online redo log file? Records all database changes. The Oracle commit command writes all the log buffers to the redo log so that all changes will become permanent changes. After commit, your data file has not changed immediately. If your database is closed at this time, you may need to clear the database files by redo log when starting the next time.

Why archive? If you performed a full database backup last night, a database problem occurred this afternoon. You need a recover. When will you need a recover? If you do not have archived all log files, you can only restore it to the time you backed up last night. However, if your database breaks down, you have all archived since the backup last night and the redo log files before today, and the last online redo log file is also good, you can recover to point of failure.

You can read the rest of the books by yourself. Don't ask how to automatically archive log files.