What is Oracle's archive log?

Our Oracle database defaults to non-archive mode, and if there are three redo log groups, when all three log groups are fully filled, the first log group will start looping, and the contents of the first log group will be completely overwritten, so if the database crashes and you want to recover the data that was earlier, That's a pit.

What to do?

You ask me, I tell you. Switching the database log mode to archive mode is OK, so when writing to the log loop, the data in the log group is written to the archive log before it is overwritten. You see, the problem is solved, right?

One might ask, " hey, when should I use the archive model?"

This depends on the database corresponding to the application system is what the requirements, if the data is absolutely not allowed to lose must use the archive mode.

If you only emphasize the operational efficiency of the system, as for data loss is not so important, you can take a non-archival mode. However, it is recommended that administrators regularly perform a full database backup.

Toggle Log Mode:

① View Log Mode

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② shutting down the database, restarting and loading the database but not opening the database

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③ Changing the log mode

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④ Opening a database

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OK, you can check the archive mode by using the Select Log_mode from V$database in the Plsql developer tool, or by entering the Sql*plus log list in archive.

A.

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B.

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If you still want to know something else, please baidu it yourself!

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What is Oracle's archive log?