How to recover accidentally deleted table in oracle

There are two methods to recover accidentally deleted Oracle tables: use rollback segment: to recover the recently deleted table, the steps include: query the rollback segment, create a temporary table, copy the data, and delete the temporary table. Using backups: Recover deleted tables that are older or have unavailable rollback segments, including using RMAN, Expdp, or Cold Backup to restore the tables.

How to recover an accidentally deleted Oracle table?

In Oracle database, accidentally deleting a table is a headache because it may lead to data loss. However, there are ways to recover accidentally deleted tables, depending on the database configuration and backups.

Method 1: Use rollback segment

• Oracle database maintains an area called rollback segment, which is used to store undo information of committed transactions.
• If the accidental deletion operation occurs in the latest transaction, the information of the deleted table can be found in the rollback segment.
• To restore a table using rollback segments, perform the following steps:

<code class="sql">-- 查询回滚段中已删除表的详细信息
SELECT * FROM V$UNDOSTAT WHERE NAME = '表名';

-- 创建一个临时表来存储已删除数据
CREATE TABLE temp_table AS SELECT * FROM RECYCLED_TABLE WHERE OBJECT_ID = (SELECT OBJECT_ID FROM sys.DBA_OBJECTS WHERE OBJECT_NAME = '表名');

-- 将已删除的数据从临时表复制到新表中
INSERT INTO 新表 SELECT * FROM temp_table;

-- 删除临时表
DROP TABLE temp_table;</code>

Method 2: Restore using backup

• If the accidental deletion operation occurs in a transaction where the rollback segment is unavailable or has been deleted for a long time, you need to use a backup to restore the table.
• Oracle Database offers a variety of backup options, including RMAN, Expdp, and Cold Backup.
• To restore a table using a backup, perform the following steps:

<code class="sql">-- 使用 RMAN 恢复表
RMAN> RESTORE TABLE 表名;

-- 使用 Expdp 恢复表
EXPDP SCHEMA=用户名 TABLES=表名 DIR=备份目录 DUMPFILE=备份文件;

-- 使用 Cold Backup 恢复表
-- 复制数据库文件
-- 重新创建数据库
-- 导入数据</code>

Precautions

To prevent data loss, the following precautions are recommended Measures:

• Back up the database regularly.
• Enable Oracle Flashback technology.
• Check database logs and alarms regularly.
• Fully test and verify database operations.

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