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Our Oracle database defaults to non-archive mode. Suppose there are three redo log groups. When all three log groups are full, the first log group will start to record circularly, and the contents of the first log group will be completely overwritten. In this way, if the database crashes, it is better to recover the data from a long time ago.

What should I do?

Ask me, I'll tell you. Switching the database log mode to archive mode is OK, so that when the log cycle is written, the data in the log group will be written to the archive log first, and then overwritten. You see, that's the problem, right?

One might ask: well, when exactly should archiving be adopted?

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

If only the operational efficiency of the system is emphasized, and data loss is not so important, a non-archive mode can be adopted. However, it is recommended that administrators regularly perform full database backups.

Switch log mode:

① View log mode

② Close database, restart and load database without opening database

Change the journal mode.

④ Open database

OK, archive mode can be viewed in PLSQL developer by selecting log_mode from v$database; or by typing archive log list in SQL*plus.

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