What temporary files can be deleted by oracle database?

Oracle temporary files can be divided into deletable temporary files generated by user sessions and background processes, as well as key temporary files inside the system and in Oracle's own operation, which cannot be deleted. Temporary tablespace usage can be viewed through SQL statements, but deleting files directly is very dangerous unless it is operated by a professional if the database is closed and there is a complete backup and recovery plan. Regularly cleaning up excessive temporary tablespaces can optimize performance. Careful operation is crucial. Be sure to back up the database before modifying it. If you have any questions, please seek help from a professional.

The Ghost of Oracle Database Temporary Files: Cleanup and Risk

Many friends have asked me if the messy temporary files in the Oracle database can be deleted, and will there be problems if they deleted? The answer is: Can be deleted, but be cautious! This is not a simple saying "can be deleted but not deleted". There are many secrets of the internal mechanism of the database and potential risks behind it.

The purpose of this article is to take you deep into the "deep in the soul" of Oracle temporary files, so that you can understand which files can be deleted, which cannot be touched, and how to clean them safely and efficiently. After reading it, you will be able to manage your Oracle database more confidently and avoid unnecessary trouble.

Let's talk about the conclusion first: what you can usually delete are temporary files generated by user sessions or background processes, which are usually located in temporary tablespaces. However, some temporary files inside the system and key temporary files generated during Oracle's own operation must not be moved! It's like you can delete temporary files on your computer desktop, but you can't delete system files at will, otherwise the system will crash.

So, how to distinguish these files? This requires a certain understanding of Oracle's architecture and processes. Oracle's temporary tablespace is used to store data generated by sorting operations, session-level data, and other operations that require temporary storage space. These temporary files usually end with .tmp or similar suffixes, and their life cycles are usually bound to the session or process that produced them. After the session is over, these files are usually automatically deleted. However, if the session terminates abnormally or the database crashes, these temporary files may remain in the system.

Let's look at some code examples. Although files cannot be deleted directly (it depends on your operating system permissions and Oracle configuration), we can view and manage the usage of temporary tablespaces through SQL statements:

 <code class="sql">-- 查看临时表空间的使用情况SELECT tablespace_name, file_id, file_name, bytes / (1024 * 1024) AS size_mb, autoextensible FROM dba_temp_files; -- 查看当前会话使用的临时段SELECT segment_name, bytes / (1024 * 1024) AS size_mb FROM v$tempseg_usage WHERE inst_id = USERENV('INSTANCE') ORDER BY size_mb DESC; -- (危险操作！慎用！) 如果确定某个临时文件不再需要，并且你拥有足够的权限，可以尝试删除它，但强烈建议在数据库关闭的情况下操作。 -- 以下代码仅供演示，实际操作风险自负。 -- OS-specific command to remove a file. Replace '/path/to/file.tmp' with the actual path. -- This is NOT a recommended practice. -- rm -f /path/to/file.tmp</code>

The above SQL statements can help you understand the status of temporary tablespaces. Remember, deleting files directly is an extremely dangerous operation, which can easily lead to instability or even crashes in the database. Unless you have a good understanding of Oracle internal mechanisms and have a complete backup and recovery plan, never try to delete any files manually.

Regarding performance optimization, it is necessary to regularly clean excessive temporary tablespaces. You can optimize performance by adjusting the size of the temporary tablespace, increasing the data files of the temporary tablespace, or using more efficient SQL statements to reduce the usage of temporary data. Remember, performance optimization is a continuous process that requires continuous adjustment according to actual conditions.

Finally, it is important to emphasize that any operation of Oracle databases should be cautious. Be sure to back up your database before making any changes. If you are not familiar with the management of Oracle databases, it is recommended to seek help from a professional. Remember, data security is more important than any performance optimization.

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