How to recover deleted data in oracle database
Deleted data in the Oracle database can be recovered through the following steps: Check the Recycle Bin: Enter the Recycle Bin to view the deleted data and restore it if it is there. Use Flashback Query: Use the Flashback Query command to restore data when it is not in the Recycle Bin. Use LogMiner tool: Extract deleted data by parsing redo log files.
Deleted data recovery method in Oracle database
Steps to recover deleted data
Deleted data in the Oracle database can be recovered through the following steps:
1. Check the Recycle Bin
- Enter Oracle Database, connect to the schema of the table whose data is to be recovered.
-
Execute the following query to view the deleted data available in the Recycle Bin:
SELECT * FROM BIN$DATA_OBJECTS;
Copy after login If the data you want to recover is in the Recycle Bin, execute the following query :
FLASHBACK TABLE table_name TO BEFORE DROP;
Copy after login
where table_name is the name of the table to be restored.
2. Use Flashback Query
- If the data is not in the recycle bin, you can use the Flashback Query command to restore it.
Use the following query syntax:
SELECT * FROM table_name AS OF TIMESTAMP AS OF to_date('yyyy-mm-dd hh24:mi:ss', 'YYYY-MM-DD HH24:MI:SS');
Copy after loginWhere:
- table_name is the name of the table where the data is to be restored.
- to_date Convert timestamp to Oracle date format.
3. Use the LogMiner tool
- The LogMiner tool can parse Oracle redo log files and extract deleted data.
To use LogMiner, follow these steps:
- Enable LogMiner:
ALTER SYSTEM SET log_archive_config = 'DG_CONFIG=(ASYNC,SYS.ARCHIVED_LOGS)';
Copy after login- Run the LogMiner command:
EXECUTE DBMS_LOGMNR.ADD_LOGFILE(LOGFILE => 'logfile_name'); EXECUTE DBMS_LOGMNR.START_LOGMNR(OPTIONS => DBMS_LOGMNR.DICT_FROM_ONLINE_CATALOG);
Copy after login- Use LogMiner query:
SELECT * FROM V$LOGMNR_CONTENTS WHERE SEGMENT_NAME = 'table_name' AND SCN >=SCN_START AND SCN <=SCN_END;
Copy after login- Restore data:
INSERT INTO table_name SELECT * FROM V$LOGMNR_CONTENTS WHERE SEGMENT_NAME = 'table_name' AND SCN >=SCN_START AND SCN <=SCN_END;
Copy after login
Note Matter
- Recovery of deleted data may not be fully guaranteed.
- Oracle recommends backing up the database regularly to prevent data loss.
- Before performing the recovery operation, it is recommended to test the recovery process in the environment.
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