How to use Oracle flashback technology?
Oracle Flashback technology is a technique used to restore a database to a specific point in time or before a specific transaction. It helps users quickly recover accidentally deleted or modified data without needing to restore the entire database from a backup.
Here are the steps for using Oracle flashback technology:
- Firstly, ensure that the flashback feature of the database has been enabled. You can check this by running the following SQL statement:
- Choose the flashback_on column from the v$database table.
- If the result returned is “YES”, it means that the flashback feature has been activated, otherwise it needs to be enabled.
- Use a flashback query to retrieve data from a specific point in time. For example, the following SQL statement will return all data before the specified time point:
- Retrieve all data from the table at a specific timestamp.
- table_name is the name of the table to be queried, and yyyy-mm-dd hh24:mi:ss is the point in time to be restored to.
- Use flashback queries to revert to the state before a specific transaction. For example, the following SQL statement will undo all changes made after the specified transaction:
- Restore the table named “table_name” to the state it was at system change number (SCN) “scn_number”.
- table_name is the name of the table to be recovered, and scn_number is the transaction number to recover to.
It is important to note that using Oracle flashback technology has certain prerequisites. These include having the database recovery mode set to ARCHIVELOG mode and ensuring there are enough flashback log files. Additionally, the use of flashback queries and flashback transaction queries also require corresponding permissions.
In conclusion, Oracle flashback technology is a powerful database recovery tool that can assist users in quickly recovering lost or incorrect data due to mistakes. However, it is crucial to use flashback technology cautiously to avoid causing further damage.
