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;

• If the data you want to recover is in the Recycle Bin, execute the following query :

  FLASHBACK TABLE table_name TO BEFORE DROP;

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');

  Where:

  • 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)';

  • Run the LogMiner command:

  EXECUTE DBMS_LOGMNR.ADD_LOGFILE(LOGFILE => 'logfile_name');
  EXECUTE DBMS_LOGMNR.START_LOGMNR(OPTIONS => DBMS_LOGMNR.DICT_FROM_ONLINE_CATALOG);

  • Use LogMiner query:

  SELECT * FROM V$LOGMNR_CONTENTS WHERE SEGMENT_NAME = 'table_name' AND SCN >=SCN_START AND SCN <=SCN_END;

  • Restore data:

  INSERT INTO table_name SELECT * FROM V$LOGMNR_CONTENTS WHERE SEGMENT_NAME = 'table_name' AND SCN >=SCN_START AND SCN <=SCN_END;

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.

The above is the detailed content of How to recover deleted data in oracle database. For more information, please follow other related articles on the PHP Chinese website!