oracle restore deleted table

In the daily database management process, sometimes database tables are accidentally deleted. Without timely backup measures, this process will be very difficult and time-consuming.

Fortunately, Oracle Database provides some tools and techniques for recovering deleted tables. This article will introduce several common methods to recover deleted tables.

Method 1: Use flashback database technology to recover deleted tables

Flashback technology is an important feature in Oracle database, which allows you to recover deleted tables without performing backup and recovery. table.

The steps are as follows:

1. Use the following command to view the available flashback time intervals, which will display the time range during which Oracle retains flashback data:

SELECT * FROM V$FLASHBACK_DATABASE_LOG;

2. Use The following command checks whether the table exists within the flashback time interval:

SELECT * FROM <table_name> AS OF TIMESTAMP SYSDATE-1;</table_name>

The SYSDATE-1 here refers to the day before the current time. Adjust the timestamp as needed.

3. If the log covers the time period when the table was deleted, you can use the following command to completely restore the deleted table:

FLASHBACK TABLE <table_name> TO BEFORE DROP;</table_name>

Method 2: Use the RecycleBin function

RecycleBin is a feature of Oracle Database that stores deleted objects and easily restores them when necessary.

1. Execute the following command under the user name to activate RecycleBin:

ALTER SESSION SET recyclebin = on;

2. Use the following command to list the objects that exist in the user's RecycleBin:

SELECT object_name, original_name, type FROM user_recyclebin;

3. Pass Execute the following command to completely delete the objects in RecycleBin:

PURGE TABLE <table_name>;</table_name>

Method 3: Restore deleted tables through log files

The log files of Oracle database can be used to restore deleted tables. This process needs to follow specific steps:

1. View the log file of the database to determine when the table was deleted:

SELECT * FROM v$log_history;

This will list the historical log file of the database.

2. Determine the timestamp in the log file that is closest to the time when the table was deleted.

3. Use the following command to create a redo log file that restores it to the timestamp of the deleted table (timestamp example: '08-NOV-19 05.00.27.000000000 PM'):

RECOVER DATABASE UNTIL TIME '08-NOV-19 05.00.27.000000000 PM';

4. Follow the following steps to roll back:

ALTER DATABASE OPEN RESETLOGS;
ROLLBACK;

Method 4: Use Oracle data recovery tool

If none of the above methods can recover the deleted table, you can consider using Oracle data recovery tool. For example, third-party tools such as Oracle Recovery Manager (RMAN). These tools can easily recover deleted tables.

Conclusion:

No matter which method you use, recovering a deleted table requires great care. You need to avoid new data loss or data corruption during the recovery process. Therefore, it is best not to attempt this area of ​​recovery until you have gained the necessary experience with backup and assurance operations.

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