How to recover a truncated table in Oracle?
In Oracle, using the TRUNCATE TABLE statement can delete all data in a table and release the table space. Unlike the DELETE statement, TRUNCATE TABLE directly deletes all data in the table rather than row by row. Because TRUNCATE TABLE is a DDL (Data Definition Language) statement, not a DML (Data Manipulation Language) statement, it cannot be rolled back or undone to recover the truncated table.
If you need to restore a truncated table, you can consider the following methods:
- Utilize backup: if there is a valid backup before truncating the table, you can use that backup to restore the data of the table. Restore the backup file into the database, and then use the INSERT INTO statement to insert the backup data into the truncated table.
- By using Flashback Table: If Oracle’s Flashback feature was enabled before truncating a table, you can use the FLASHBACK TABLE statement to restore the table to a previous state. For example, you can use the following statement to revert the table to its state from one hour ago.
- Restore the table “table_name” to its previous state one hour ago.
- This will restore the table to a specific time point using the Flashback feature.
- Using log files: If the database has logging enabled, log files can be used to recover truncated tables. Utilize Oracle’s LogMiner tool to parse the log file and extract data from the truncated table.
- It is a complex task to use log files to recover a truncated table, requiring a thorough understanding of Oracle logs and the recovery process. It is recommended to seek assistance from an experienced DBA to perform this operation.
Please note that these methods only apply if there are available backups or logs before the table is truncated. Recovering a truncated table can be very difficult or even impossible without backups or logs. Therefore, before performing a TRUNCATE TABLE operation, make sure you have backed up important data and are certain whether truncating the table is necessary.
