Detailed explanation of Oracle query table lock status method

Detailed explanation of Oracle query table lock status method

In database operations, table lock is a very important concept, it will affect the database performance and concurrency. This article will introduce in detail the method of querying table lock status in Oracle database and give specific code examples.

1. Method of querying table lock status

In Oracle database, we can obtain table lock status information by querying in the system view. The following are some commonly used system views:

• V$LOCK: View that displays advanced lock information in the database
• DBA_BLOCKERS: Display Current session ID and locked session ID
• DBA_WAITERS: Displays the current session ID and waiting session ID
• DBA_DML_LOCKS: Displays the current session holder and waiting DML lock information

2. Specific code example

2.1 Query the lock session on the table

SELECT c.object_name,
       b.sid,
       b.serial#,
       b.username,
       b.status,
       b.server,
       l.locked_mode,
       l.lock_type
FROM   v$locked_object l,
       dba_objects c,
       v$session b
WHERE  l.object_id = c.object_id
AND    l.session_id = b.sid;

This code can query all the locks in the current database The locking session information of the table, including session ID, user holding the lock, lock type, etc.

2.2 Query the waiting and waiting lock information of the current session

SELECT session_id, 
       lock_type,
       mode_held,
       mode_requested
FROM   dba_dml_locks
UNION
SELECT holding_session session_id,
       holding_cursor_type lock_type,
       MODE_HELD mode_held,
       MODE_REQUESTED mode_requested
FROM   dba_kgl_locks

This code can query the lock information held and waiting for the current session, which can help us better understand the current database Lock details.

3. Summary

Through the above introduction, we have learned about the method of querying table lock status in Oracle database, and given specific code examples. In actual operation, by monitoring the table lock status, we can better optimize the performance of the database and improve the concurrent processing capability of the system. Hope this article is helpful to you.

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