oracle delete table data file

Oracle is a popular relational database management system that can easily manage large amounts of data. When you need to clear data in a database, a common way is to delete the data in a table. However, simply deleting is not enough because Oracle Database will also retain the data files of the deleted data. If you wish to completely delete the data, including the data files, then you need to follow certain steps to delete the table's data files.

The steps to delete a table's data file are as follows:

1. First, you need to determine which table's data file you want to delete. You can query the space occupied by the table through the following command:

SELECT tablespace_name AS "表空间",
       owner AS "所有者",
       segment_name AS "表名",
       segment_type AS "表类型",
       bytes/1024/1024 AS "大小（MB）"
FROM dba_segments
WHERE owner = '表的所有者'
  AND segment_name = '待删除的表名';

2. If you confirm that you want to delete the data file of the table, please clear the table first. All data in the table can be deleted with the following command:

DELETE FROM 表名;
COMMIT;

Note that you need to be very careful with this operation because it will permanently delete the data.

3. Close table:

ALTER TABLE 表名 DISABLE TABLE LOCK;

This command will lock the table to prevent other users from accessing it.

4. Delete the data file of the table from the disk. You can use the following command to delete the table space:

DROP TABLESPACE 表空间名 INCLUDING CONTENTS;

Note that here, you must confirm the use of the INCLUDING CONTENTS option, otherwise Oracle can only delete the pointer to the data file.

5. Finally, use the following command to remove the table lock:

ALTER TABLE 表名 ENABLE TABLE LOCK;

This command releases the lock associated with the table and allows other users to access the table.

It should be noted that performing these deletion operations may be risky, so its feasibility should be tested in a test environment. If you don't feel safe, it's best to back up your database. Regardless, when you are preparing to delete data, you should carefully evaluate the risks and benefits and ensure that appropriate decision support mechanisms have been put in place.

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