Reason why oracle is locked

Oracle database may be locked during operation, that is, some resources are temporarily locked to ensure data integrity and consistency. But when any user is locked, it will affect the normal operation of the entire system. So, what are the reasons for the Oracle database to be locked?

1. Lock contention

Most locks in Oracle database are performed at the table, row, or partition level, and these locks are requested by different sessions . If multiple sessions request locks at the same time, lock contention may result, in which case the database will be locked. In order to avoid lock competition, you can adjust the lock level or reduce the impact of multiple client concurrent requests on the same resource.

2. Locked

Sometimes locked sessions may have a deadlock situation waiting for each other to release the lock. If multiple transactions wait for a lock held by another transaction, and this transaction waits for a resource held by another transaction, a deadlock will occur. Oracle Database Management System provides a number of deadlock detection techniques to solve this problem, including automatic deadlock detection, manual deadlock detection, and specialized deadlock analysis tools.

3. Lock timeout

Sometimes, the lock held by the session exceeds a threshold time, because the lock is held for too long, or even permanently, resulting in Other sessions cannot access the resource. To avoid this from happening, you can set a lock timeout to automatically release the locked resource and allow other sessions waiting for the resource to acquire the lock.

4. Excessive locking

Sometimes, a session may overuse locks, causing resource competition and database performance degradation. If a session keeps trying to acquire the lock during execution without giving other sessions any chance to acquire the resource, it will cause a deadlock or the database will be locked. To avoid lock overuse, query and locking logic need to be optimized.

5. The database is not maintained

If the Oracle database is not maintained frequently, the operating efficiency of the database will be reduced, and the chain reaction in the lock event will also increase to an unbearable level. Degree. Therefore, it is very important to maintain the database regularly, including operations such as data cleaning, space management, and index optimization.

In short, there may be many reasons why the Oracle database is locked, but through reasonable management and optimization, the probability of locking can be greatly reduced and the stability and performance of the entire system can be improved.

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